Encyclopedia of Japanese Small Arms 🇯🇵

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BOLT-ACTION RIFLES №1

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BOLT-ACTION RIFLES

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Murata rifles

The Murata Type 13, adopted in 1880, was the first domestically designed standard Japanese military rifle, created by Major Murata Tsuneyoshi. It was a single-shot bolt-action rifle chambered for an 11 mm cartridge. The design combined features of contemporary European rifles, using a bolt system similar to the French Gras Model 1874 and a firing mechanism influenced by the Dutch Beaumont Model 1871.

This rifle marked the starting point of Japan’s independent small-arms development but was soon found to need structural improvements.

Top: Type 13 Murata rifle. Bottom: Type 18 Murata rifle.

In 1885, the improved Murata Type 18 was adopted to address shortcomings of the Type 13. The main modifications included:

• A strengthened bolt and receiver for improved durability.
• Minor structural reinforcements to the stock.
• Adjustments to sights and standardization of ammunition and bayonet dimensions.

Although still a single-shot rifle using the same 11 mm cartridge, the Type 18 proved more reliable and became the most widely produced Murata single-shot rifle.

Alongside the standard infantry rifle, a Murata Type 18–based cavalry carbine was produced for mounted troops and support units. It retained the 11 mm cartridge and single-shot bolt-action mechanism of the Type 18 rifle but featured a shorter barrel and reduced overall length, improving handling on horseback and in confined conditions.

Top: Type 18 Murata carbine. Bottom: Type 22 Murata carbine.

The earliest Japanese silencer was developed by Kanshiro Fukumura for the 11mm Type 18 Murata rifle and patented on February 15, 1894. This multi-functional muzzle device was designed to reduce gunshot noise and suppress smoke, while also facilitating partial reloading by using a movable mechanical attachment and rod to automatically open the bolt after a shot.

​Patent drawing of Kanshiro Fukumura’s silencer.

A major technological step occurred with the adoption of the Murata Type 22 in 1889. This model introduced several fundamental changes:

• Reduction of caliber to 8 mm, improving ballistic performance.
• Adoption of a tubular magazine under the barrel, making it Japan’s first repeating service rifle.
• Compatibility with smokeless powder ammunition, placing it on par with contemporary European designs such as the French Lebel Model 1886.

Despite these advances, the tubular magazine system was already becoming obsolete compared to emerging box-magazine rifles.

Type 22 Murata rifle.

At the same time, a shortened Murata Type 22 Carbine was introduced for cavalry, artillery, and support troops. It featured:

• The same 8 mm cartridge as the standard Type 22 rifle.
• A shorter barrel and overall length for improved handling.
• A shortened tubular magazine.
• An otherwise identical bolt and firing mechanism to the rifle version.

The carbine shared the same limitations as the rifle and saw limited service before being surpassed by more modern magazine-fed weapons.

Specification	Murata Type 13 Rifle	Murata Type 18 Rifle	Murata Cavalry Carbine	Murata Type 22 Repeating Rifle	Murata Type 22 Repeating Carbine
Caliber	11 mm	11 mm	11 mm	8 mm	8 mm
Overall length	1294 mm	1278 mm	1178 mm	1207 mm	960 mm
Length with bayonet	1859 mm	1737 mm	—	1476 mm	—
Weight	4156 g	4098 g	3600 g	4123 g	3700 g
Weight with bayonet	4899 g	4759 g	—	4519 g	—
Muzzle velocity	436 m/s	460 m/s	413 m/s	610 m/s	593 m/s
Effective range	1500 m	1500 m	1200 m	2000 m	1300 m
Magazine capacity	—	—	—	8 rounds	5 rounds
Bullet weight	26 g	27 g	27 g	16 g	16 g

In 1900–1901, the Imperial Japanese Navy considered a project for a deep modernization of the Murata rifles, proposed by Kinjiro Motooka, a technician at the Tokyo Arsenal. The primary goal was to replace the obsolete and dangerous tubular magazine with a modern box system, which increased the rate of fire and improved safety during handling.

Early Murata magazine rifle.

Motooka’s design featured a 5-round magazine that was attached to the receiver with two screws and integrated with the trigger guard. В In the improved 1901 version, the engineer managed to make the mechanism compact—it barely protruded beyond the stock’s dimensions.

Late Murata magazine rifle.

Despite the successful refinement and an order to produce one experimental prototypes in February 1901, the project was rejected. A technical committee led by Admiral Togo Heihachiro made the final decision to transition to the new Arisaka rifles (Type 30), deeming the modernization of the old Murata platform impractical.

Late Murata magazine rifle.

Currently, a private collection contains two rifles referred to as Murata magazine rifles. However, both of them raise a great deal of suspicion. One of the rifles (a carbine, to be precise) features a Type 44 carbine bayonet, which was not adopted until 1911. By that time, the unification of Arisaka rifles was well underway. Given that the Navy had already abandoned the Murata magazine rifle as early as 1901, it seems highly improbable that the military would revert to Murata rifles for the cavalry, especially since new weapon models were being specifically developed for them at the time. As far as is known, these weapons underwent restoration for 15 years, with components purchased separately. It is possible that, in this case, the weapon was either simply restored incorrectly or is an outright fabrication that has no actual connection to an authentic Murata magazine rifle.

Late Murata magazine carbine.

A second Murata magazine rifle was auctioned off with the following description:

“This experimental Japanese Murata fixed box magazine rifle is most likely unique. The Japanese began experimenting with box fed magazine rifles around October, 1885. The experimentation continued until March, 1889, when the Type 22 with its under barrel tube magazine was adopted. The top of the chamber of this box magazine rifle is numbered 1. The overall length is approx. 48.25”. The 30" barrel has an excellent bore with bright, strong rapid twist rifling. The caliber is most likely 8mm Japanese as found on the Type 22 rifles. The gun has approx. 95% blue with the butt plate being faded. The cleaning rod and bolt are bright. The ladder rear sight is graduated from 30 to 80 on the side and 9 to 22 on the leaf. The left side of the receiver is marked in script “Fusil a repetition Mourata” over “a 5 coups” with the magazine box having “anee 1887”. This translates from French to Murata repeating rifle with 5 shots in the year 1887. It is unclear whether this is an original marking or whether it was added at a later date by a Frenh museum. The left side of the receiver is equipped with a sliding magazine cut off. The two piece stock is very good with various storage nicks and dings. It is unmarked. The nose cap, with bayonet lug, is very similar to the early Type 22 Murata rifle nose cap. The rifle is equipped with a functioning grip safety. The actin functions correctly. This interesting and most unusual Murata rifle is fit for the most advanced collection of Japanese rifles or early magazine rifles."

Unfortunately, no documentation has been found to confirm development work on any magazine types other than the tubular ones for the Type 22 Murata rifle between 1885 and 1889. The French inscriptions also raise questions. It remains unclear to what extent this weapon is actually Japanese and whether it was ever intended for the Japanese Army or Navy.

Late Murata magazine rifle.

Type 30 Rifle

In the late 19th century, the Japanese military recognized the need for a profound modernization of its small arms. The primary goal was to replace the Murata rifle, which featured a cumbersome under-barrel tubular magazine, with a modern system utilizing a central box magazine. This development project was led by Artillery Colonel Arisaka Nariakira and Major Mimoto Michimichi. During the search for optimal ballistic characteristics, three types of experimental rifles were produced and tested in 7 mm, 6 mm, and 6.5 mm calibers. Based on the test results, the 6.5 mm caliber was deemed the most effective and was officially adopted in February of the 30th year of the Meiji era (1897) under the designation Type 30.

Type 30 rifle.

​The selection of such a small caliber sparked serious debate within the Artillery Committee. Colonel Iguchi Shogo opposed the choice, labeling the 6.5 mm bullet “non-lethal,” but the prevailing opinion was that it was sufficient to simply disable an enemy on the battlefield rather than inflict unnecessarily cruel injuries. The new rifle utilized smokeless powder cartridges and bullets with a copper-nickel jacket. Loading was performed using 5-round clips, which significantly simplified operation in combat compared to the Murata system. The rifle saw its baptism by fire during the Russo-Japanese War, where it proved its effectiveness; soldiers could carry a larger ammunition load, and according to medical reports, wounds from the high-velocity bullets healed faster, allowing soldiers to return to the front sooner.

​In addition to the infantry model, a cavalry carbine was created based on the Type 30, with production beginning in 1899. It was 300 mm shorter than the standard rifle, featuring a 480 mm barrel compared to the 790 mm barrel of the infantry version. For the convenience of riders, the sling swivels were moved to the left side of the weapon. Initially, the carbine did not have a bayonet lug because the cavalry of that time relied on sabers, but the specification was changed in 1906 to allow for a bayonet.

Type 30 carbine.

Under wartime conditions, production was increased to 1,000 units per day, and due to a shortage of high-quality walnut, stocks were often made from beech. Despite post-war discussions about switching to larger calibers following the European example, the experience of World War I confirmed that 6.5 mm remained an ideal solution for the army.

Specification	Type 30 Rifle	Type 30 Carbine
Caliber	6.5 mm	6.5 mm
Overall Length	1275 mm	965 mm
Length with Bayonet	1665 mm	—
Weight	3850 g	3180 g
Weight with Bayonet	4290 g	—
Muzzle Velocity	700 m/s	650 m/s
Sighting Range	2000 m	1500 m
Magazine Capacity	5 rounds	5 rounds
Cartridge Weight	11 g	11 g

Type 35 Rifle

Subsequently, Artillery Captain Kijiro Nambu of the Army Technical Bureau directed the modernization of the Type 30 infantry rifle. This development resulted in the Type 35 rifle, specifically configured for naval service. While the Type 35 maintained structural continuity with the Type 30 design, the primary technical refinements included the integration of a sliding receiver dust cover and the implementation of a tangent leaf rear sight.

Type 35 rifle.

Specification	Type 35
Caliber	6.5 mm
Overall Length	1275 mm
Length with Bayonet	1665 mm
Weight	3850 g
Weight with Bayonet	4290 g
Sighting Range	2000 m
Magazine Capacity	5 rounds
Cartridge Weight	11 g

Type 38 Rifle

In May 1904, Captain Nambu initiated modifications to the bolt assembly and receiver of the Type 30 infantry and cavalry rifles. Although the project had reached the testing phase, further research was temporarily suspended due to the outbreak of the Russo-Japanese War. Following the cessation of hostilities and incorporating combat feedback, a prototype featuring a dust cover was finalized. On May 5, 1906, the Type 38 infantry rifle and cavalry carbine were formally adopted into service.

Type 38 rifle.

The Type 38 design offered several advantages over contemporary foreign counterparts. The bolt group, comprised of only five components, was three parts simpler than the then-advanced Mauser system. The simplified field-stripping procedure and the ergonomic design of the safety catch facilitated effective operation in harsh environments, specifically allowing for manipulation while wearing heavy gloves. Furthermore, the detachable nature of the dust cover improved the weapon’s practical utility and maintenance efficiency under field conditions.

Based on the Type 38 infantry rifle, a shortened variant was developed for cavalry use, featuring an overall length of 976 mm—approximately 300 mm shorter than the standard infantry model.

Type 38 carbine.

Specification	Type 38 Rifle	Type 38 Carbine
Caliber	6.5 mm	6.5 mm
Overall Length	1276 mm	955 mm
Length with Bayonet	1670 mm	1347 mm
Weight	4100 g	3400 g
Weight with Bayonet	4490 g	3780 g
Muzzle Velocity	762 m/s	708 m/s
Sighting Range	2400 m	2000 m
Magazine Capacity	5 rounds	5 rounds
Cartridge Weight	9 g	9 g

At the end of the war, a modified Type 38 rifle was spotted featuring a 30-round magazine from the Type 96 light machine gun.

Type 38 with a Type 96 machine gun magazine.

In 1927, Japanese inventor Kinzaburo Hibino developed an advanced silencer design based on H.P. Maxim’s concepts. The device utilized two main expansion chambers and a series of conical baffles to effectively suppress sound by separating propellant gases. A unique feature included two side tubes designed to vent gases from the outer shell and simplify mounting on rifles or machine guns. Hibino’s project was notable as one of the first silencers intended for use on automatic weapons.

​Patent drawing of Kinzaburo Hibino’s silencer.

In August 1931, the Imperial Japanese Army’s Technical Headquarters conducted firing tests using a Type 38 rifle equipped with a foreign-made silencer. These trials, which utilized standard 6.5×50mm SR ammunition, confirmed the device’s effectiveness in sound suppression and terminal ballistics against live targets. The final report was forwarded to Army Intelligence (“Unit No. 33”) in China, and the successful results led to the official approval of the procurement and testing expenses.

In 1933, Japanese inventor Rihei Katori applied for a patent for a “rifle noise suppressor” designed to reduce the expansion velocity of propellant gases by a factor of four. The device consisted of a double-walled metal cylinder containing a helical baffle (a twisted steel strip) welded to support disks. A system of graduated perforations in the internal and external housings effectively fragmented and rapidly cooled the exhaust gases. The “Katori suppressor” utilized a collet chuck mounting system similar to the Maxim silencer and was officially reviewed by the Army Technical Headquarters.

​Patent drawing of Rihei Katori’s silencer.

In 1934, Masatsugu Takaishi filed a patent for a flash and noise suppressor. The device featured a unique dynamic telescopic design: upon firing, the propellant gas pressure forced the external housing forward, stretching four external springs, while the internal spiral baffle unit compressed an internal return spring. Once the gases were vented through three rows of apertures in the muzzle attachment, the spring system returned the components to their original position. This mechanism allowed the device to momentarily increase its internal volume to maximize the suppression of both muzzle flash and report.

​Patent drawing of Masatsugu Takaishi’s silencer.

In 1929, the renowned designer Kijiro Nambu filed a patent for a unique training device intended to mitigate the negative effects of muzzle blast on student marksmen. The attachment was designed to resemble a standard bayonet; however, instead of a blade, it featured a hollow tube that fitted directly over the rifle barrel. During training exercises, the muzzle flash and report were contained within the tubular shroud. This design reduced the concussive impact of the shot on both the shooter and nearby observers, facilitating a more comfortable learning environment for recruits.

​Patent drawing of Kijiro Nambu’s silencer.

Type 44 Carbine

The Type 44 cavalry carbine was developed based on the experience of the Russo-Japanese War, which demonstrated that cavalry in actual combat were often forced into dismounted engagements. Under such conditions, the use of traditional sabers was limited, and they hindered the rapid movement of soldiers. Taking into account the European trend of equipping carbines with bayonets, the Japanese Minister of War ordered research in May 1909 to create a domestic carbine with a permanently attached bayonet. By September of that same year, the Army Technical Department produced an experimental batch of 30 units for testing.

Practical trials at the Cavalry School confirmed that the new bayonet design did not cause fatigue among soldiers and was comfortable to carry. Furthermore, the durability of the weapon was deemed sufficient, and its shooting accuracy was found to be even higher than that of the Type 38 carbine due to easier aiming and lighter recoil. The school concluded that integrating the blade directly into the carbine’s design avoided unnecessary weight while maintaining the mobility of cavalry units.

Type 44 carbine

The Type 44 carbine was officially adopted for service on December 30, 1910. Structurally, it largely followed the Type 38 system but was distinguished by a needle-style triangular bayonet on a hinge, which folded into a groove in the stock when not in use. The carbine weighed 3.92 kg, and its total length with the bayonet deployed reached 1.315 meters. Later, in 1912, this weapon officially replaced revolvers for cavalry non-commissioned officers.

Late Type 44 carbine.

During subsequent field use, a problem was identified regarding a significant drop in accuracy when firing with the bayonet deployed. Investigations conducted between 1927 and 1928 established that the cause was barrel vibrations transmitted through the stock mounting elements. To correct this defect, a series of modernizations were carried out (the Ko and Otsu variants), during which the clearances between the barrel and the mounting parts were modified to stabilize the point of impact.

Top: Standard early variant. Middle: Type Ko variant. Bottom: Type Otsu variant.

Final refinements to the design were completed by 1934, when a new rear sight scale was officially approved to account for the corrected ballistics. Parallel to the modernization of the carbine itself, work was conducted on related equipment; in 1933, special hemp ammunition belts were developed. Of the two proposed versions, the Ko type belt was adopted, featuring six compartments for ammunition and two special pockets for hand grenades.

Specification	Type 44 Carbine
Caliber	6.5 mm
Overall Length	955 mm
Length with Bayonet	1309 mm
Weight	3965 g
Muzzle Velocity	708 m/s
Sighting Range	2000 m
Magazine capacity	5 rounds
Cartridge Weight	9 g

Type Heiki Rifle

The Type Heiki was a proprietary military rifle project proposed by the private firm Nippon Heiki Seizo Co., Ltd. (Japanese Ordnance Manufacturing), based in Osaka, during the late Taisho era. On November 15, 1917, the company submitted a formal application to War Minister Kenichi Oshima for the trial production of military rifles.

The project’s primary technical consultant was Shinjiro Kobayashi, a retired Colonel of Artillery. Kobayashi brought extensive expertise from the Tokyo Artillery Arsenal and had previously conducted state-sponsored studies of firearms manufacturing in the United States, Germany, France, and Great Britain. His influence is evident in the design’s departure from standard Japanese ordnance toward Western, specifically British, engineering concepts.

Type Heiki rifle

The barrel was constructed from high-grade special steel with a 6.5 mm caliber and a total length of 760 mm. The bore featured six-groove rifling. The sighting system utilized a fixed base zeroed at 350 meters, with a maximum graduation extending to 2,500 meters. The projected muzzle velocity was 800 m/s, a figure notably higher than the standard Type 38 Arisaka (762 m/s).

The receiver featured a unique rectangular aperture located above the chamber area. This design allowed for a visual confirmation of cartridge seating and served as a gas relief port to divert pressure away from the shooter in the event of a case rupture. The bolt action was designed for high-speed operation, allowing the cycle to be completed in a single, angled motion.

A defining feature of the Type Heiki was its 10-round capacity, achieved through a vertical box magazine. This doubled the capacity of the Imperial Japanese Army’s standard Type 38 and Type 44 rifles (5 rounds). The magazine utilized a single-plate leaf spring rather than a coil spring, intended to reduce mechanical failure and optimize internal space.

A safety lever was positioned behind the trigger guard. The rifle utilized a “safe fire” system where the sear would not release unless the safety lever and the trigger were depressed simultaneously, preventing accidental discharge upon impact. To mitigate heat transfer, a “radiator wall” made of soft iron with granular protrusions was installed between the barrel and the wooden stock. This component was designed to accelerate cooling and prevent the walnut or beech-wood furniture from charring during sustained fire.

Nippon Heiki Seizo possessed a substantial industrial base, with a facility covering approximately 1.85 hectares and employing 2,500 workers. However, the project faced significant procurement hurdles. Despite receiving official permits from the War Ministry (December 1917) and the Home Ministry (March 1918), the production of the 500-unit trial batch was paralyzed by supply chain disruptions. By July 1918, the barrel-grade steel—which was strictly regulated by the Ministry of Agriculture and Commerce—had failed to arrive. Historians suggest this was due to the extreme demand for domestic steel by state arsenals during World War I, which left private manufacturers with little to no raw materials.

There is currently no definitive archival evidence to confirm that a functional prototype of the Type Heiki was ever completed. While the technical plans and industrial preparations were exhaustive, the subsequent fate of the project remains unknown, and no surviving examples have been identified in historical collections.

Type 97 Rifle

Systematic research into the development of optical sights for small arms was initiated in Japan on July 20, 1920. During the early stages, Japanese engineers relied on the study of foreign expertise, specifically products from the German company Carl Zeiss. However, in 1923, a fire at the Army Technical Bureau destroyed most of the early documentation, which significantly impeded research efforts. That same year, the Nippon Kogaku company (now Nikon) was commissioned to develop the first domestic prototypes. Initial trials conducted in 1928–1929 revealed serious design flaws, including instability of the mounting system and spontaneous shifting of the reticle under recoil.

A prototype Japanese 4x optical sight mounted on a Type 38 rifle.

The lack of urgent demand from the military restrained the project until 1931. The outbreak of the Manchurian Incident abruptly shifted priorities, highlighting the critical need for precision weapons in positional and mountain warfare. In 1932, a prototype with 4x magnification was introduced. For large-scale field evaluations of this concept, the Kokura Arsenal produced a pre-production batch of 700 Type 38 rifles equipped with optics designated as the Type 5 (this appears to be an unofficial designation used exclusively by auction houses).

Experimental Type 38 sniper rifle equipped with a Type 5 optical sight.

More photos

Type 5 optical sight.

Diagram of the Type 38 sniper rifle mount for the Type 5 optical sight.

Type 38 sniper rifle equipped with a Type 5 optical sight. Note the absence of the rubber eyecup, which has been lost.

However, field trials in North Manchuria in 1933 demonstrated that high magnification was redundant; it significantly increased the weapon’s weight and hindered rapid target acquisition. Between 1934 and 1936, the focus shifted to the development of a more compact 2.5x magnification sight.

A key technical challenge remained the movable reticle used for adjustments, which frequently shifted due to recoil forces. Engineers adopted a radical solution: fixing the reticle permanently and etching a range scale (ballistic drop compensation) directly onto the lens to provide aiming angles.

Final refinements were completed by June 1937. Following successful accuracy and durability tests conducted at the Futtsu Proving Ground, the design was deemed satisfactory. In February 1938, an official petition was submitted to adopt the sight into service under the designation Type 97. This sight became the standard optic for the sniper rifle of the same name and was installed into a dedicated dovetail mount on the left side of the receiver, ensuring secure fixation and high ballistic performance. The distinguishing feature of the Type 97 sniper rifle was the inclusion of a monopod; otherwise, it remained identical to the Type 38 rifle.

Type 97 sniper rifle.

Specification	Type 97 Rifle
Caliber	6.5 mm
Overall Length	1276 mm
Weight	4840 g
Muzzle Velocity	762 m/s
Magazine capacity	5 rounds
**Cartridge Weight **	9 g

Type Mo Rifle

In 1938, Army Minister Itagaki issued an order to Kumura, the head of the Army Technical Headquarters, regarding the purchase of rifles. To commemorate the conclusion of the Anti-Comintern Pact between Japan, Germany, and Italy, German Mauser rifles and Italian Carcano rifles were purchased and adopted as “semi-standard” weapons. The order specified the acquisition of 30,000 Italian standard rifles and 8,000 original Mauser rifles. While officially intended for use in Manchukuo, the purchase also served external diplomatic purposes.

Type I rifle.

The Type Mo rifles consisted of the German Mauser Standard Model 1924 and the Czechoslovakian ZB (vz. 24).

• Type I: Designed for infantry use.
• Type II: Designed for cavalry use.
• Type III: Designed for both infantry and cavalry use.
• Caliber and Ammo: The caliber was 7.92 mm, utilizing German S, SS, and SmK ammunition.
• Performance: The muzzle velocity for S-type bullets was 830 m/s, and for SS-type bullets, it was 760 m/s. The sighting range spanned from 100 to 2,000 meters.

In May 1939, tests at the Futtsu Proving Ground compared these models to the experimental Japanese Type 99 rifle. While the Mauser’s accuracy was comparable to the Type 99, the Czechoslovakian vz. 24 was found to be slightly inferior.

Type II rifle.

Several structural disadvantages were noted during testing:

• The rifles lacked a bolt stop (a pin to prevent the bolt face from rotating), creating a risk of the firing pin dropping if the bolt was not fully closed.
• Unlike the Japanese Type 38, they lacked a bolt cover, making them less effective against dust.
• While the Mauser was a superior rifle, the Italian Carcano batch included low-quality rifles manufactured by civilian hunting companies.
• Some of these Italian rifles became inoperable after only a few shots, which was so severe it led to disciplinary discussions regarding the inspectors.

Despite these issues, political considerations prevailed, and the rifles were deemed practical for frontline use. In October 1939, the Type Mo system was officially adopted as a “semi-standard” weapon along with its corresponding bayonets.

Specification	Type I (Mauser Model 1924 rifle)	Type II (Mauser Model 1924 carbine)	Type III (ZB vz. 24)
Total Length	1108 mm	1100 mm	1095 mm
Full Weight	3.950 kg	4.090 kg	4.110 kg
Bayonet	Type I	Type II	Type III

Type I Rifle

The Type I rifle utilized the action of the Italian Type 91 infantry rifle (Carcano), while other parts adopted the design of the Type 38 infantry rifle. It was purchased from Italy for the same reasons as the “Type Mo” (Mauser) rifle and was primarily assigned to second-line infantry units.

It was officially adopted in December of the 15th year of Showa (1940). The caliber was 6.5mm; it used the clips and ammunition of the Type 38 rifle and was equipped with the Type 30 bayonet.

Type I rifle.

In addition to being issued for training purposes to groups such as the Youth Corps, this rifle was also used by the Navy. There were two variants of this rifle.

Specification	Type I
Weight	4.35 / 4.47* kg
Weight with bayonet	4.823 /4.943* kg
Total length	1.26 / 1.287* m
Length with bayonet	1.644 / 1.671* m
Barrel length	0.781 m
Magazine capacity	5 rounds
Sighting range	300 ~ 2400 m

*Note: Specification of the other version.

[_DELAVR]

BOLT-ACTION RIFLES №2

Type 99 Rifle

The primary impetus for transitioning from 6.5 mm to 7.7 mm caliber was the low stopping power of the 6.5 mm bullet and the lack of ammunition interchangeability between rifles and heavy machine guns.

• Modified Type 38 Rifle (1919): In October of the 8th year of the Taisho era, ballistic testing began on Type 38 rifles that had been re-barreled for 7.7 mm caliber. One hundred units were delivered to the Infantry School for field trials.
• Modified Type 38 Carbine (1922): In July of the 11th year of the Taisho era, similar modified specimens were transferred to the Cavalry School.
• Experimental Rifle Type Ko 7,7 mm (1929): Developed by the Tokyo Artillery Arsenal (18 units produced). The design was based on mechanisms featuring low muzzle velocity and low recoil. Testing revealed critical defects: excessive muzzle pressure due to the shortened barrel, significant muzzle flash, and poor accuracy.

In April of the 1938, the Army Technical Bureau initiated the development of a new 7.7 mm rifle. Thirty units of the first-iteration prototypes were ordered.

Variant No. 1 (Nagoya Arsenal):

• Design: Based on the Type 38 rifle action, adapted for 7.7 mm caliber and simplified for mass production.
• Trials (October 1938): The specimen demonstrated satisfactory functionality and durability. It was initially equipped with a muzzle brake to reduce recoil; however, this resulted in an adverse acoustic impact (muzzle blast) on the shooter and a decrease in accuracy.
• Outcome: Deemed promising. In subsequent iterations (the second and third prototypes), the muzzle brake was removed, and accuracy was brought up to the standard of the Type 38 rifle.

Nagoya Arsenal rifle.

Variant No. 2 (Kokura Arsenal):

• Design: Involved significant modifications to the bolt group compared to the Type 38, with the goal of maximizing manufacturing simplification.
• Trials (October 1938): Instead of a muzzle brake, a recoil buffer was integrated into the buttstock. Testing revealed excessive recoil, unsatisfactory grouping (accuracy), and insufficient mechanical durability.
• Outcome: Development was terminated in January 1939 due to the inability to achieve the required reliability and the unfinished research regarding the corresponding ammunition.

Kokura Arsenal rifle.

Meanwhile, two experimental variants were also developed for the 7.7 mm carbine based on design specifications similar to the primary rifle. The first variant generally followed the design of the Type 44 carbine, incorporating necessary modifications to increase the caliber and simplify production. The second variant was similarly based on the Type 38 carbine with corresponding refinements.

In October of the 13th year of Showa (1938), the first prototypes were completed. The test results indicated the following:

• First Variant: Thanks to the installation of a muzzle brake, the recoil was softened; however, it caused painful sensations in the shooter’s ears, and the firing accuracy was low.
• Second Variant: A muzzle brake was absent, but a buffer spring was installed in the buttplate. Nevertheless, the recoil remained excessive, and the firing accuracy was also unsatisfactory.

Taking these results into account, as well as global trends in combat tactics and unit equipment, it was decided to increase the barrel length of the carbine. Furthermore, based on mobilization readiness considerations, it was deemed appropriate to abandon the division of carbines into different models (as was the case with the Type 38 and Type 44) and unify them into a single, ideal weapon type for cavalry, supply units, artillery, and mechanized troops.

Prototype 7.7mm сarbine.

Consequently, both initial variants were rejected, and the decision was made to continue research on a design based on the Type 38, but with a barrel lengthened by 15 centimeters.

In May of the 14th year of the Showa era (1939), testing of the third prototypes of Variant No. 1 was completed. The muzzle velocity was recorded at 780 m/s. The program culminated in July 1939 with the adoption of a “unified standard” for the rifle, allowing for the abandonment of separate infantry, cavalry, and artillery models.

A distinctive feature of the Type 99 was the inclusion of a monopod, similar to that of the Type 97 sniper rifle. The weapon was adapted for two types of ammunition: the “heavy ball” (13.2 g) intended for machine guns and a specially developed “light ball” (11.8 g) for rifles. A significant industrial achievement was the full interchangeability of parts, achieved through the implementation of a modern system of tolerances and gauges.

During the adoption process of the 7.7mm system, the classification separating the weapon into a Long Rifle and a Short Rifle was initially maintained. The long model was designed to closely match the dimensions of the classic Type 38 infantry rifle.

Type 99 long rifle.

It was originally intended that long rifles would be issued to line infantry, while short rifles would be supplied to cavalry, artillery, and engineer units. However, combat experience in China and global trends toward the universalization of small arms led to the rapid termination of long-model production (with only about 38,000 units manufactured). Consequently, the Type 99 Short Rifle became the primary standard for all branches of the Imperial Japanese Army, effectively combining the ballistic performance of an infantry rifle with the maneuverability of a carbine.

Type 99 short rifle.

During mass production from 1939 to 1945, the design of the Type 99 rifle underwent significant degradation driven by resource shortages and Japan’s deteriorating strategic position. Historians and collectors generally categorize this evolution into three main stages:

• Early Series (1939–1941): This period represents the peak of manufacturing quality. Rifles from this era were equipped with a full suite of accessories: anti-aircraft sight wings for firing at low-flying aircraft, a wire monopod for stability, and a sliding dust cover to protect the action. All parts featured precision fitting and a deep blued finish.
• Transitional/Mid Series (1942–1943): As combat intensity increased, systematic rationalization began. The monopods and anti-aircraft wings were the first features to be abolished, as they were deemed ineffective in actual combat conditions. While the finish on the wood and metal became rougher, the reliability of the mechanisms remained high.
• Late and “Last Ditch” Series (1944–1945): Known in the West as “Last Ditch” variants, these rifles are characterized by extreme simplification. The adjustable rear sight was replaced with a fixed peep sight, the metal buttplate with a wooden one (often nailed on), and the stocks were made from raw, poorly finished timber. In the final specimens, material quality plummeted to critical levels, frequently leading to mechanical failures and injuries to the shooter due to inferior steel tempering.

During its production period, 1940-1945, the Type 99 rifle was simplified from its original configuration, top, to the crude Substitute Type 99 (“last ditch”) variety at the bottom. Changes in many parts were implemented gradually, resulting in many variations of “transition” rifles, center. The sequence of changes incorporated by each arsenal or subcontractor was slightly different.

Type 99 Experimental Substitute Rifle (Army) — this modification was developed in 1939 at the request of the Imperial Japanese Army to reduce production costs. The core concept involved using lower-grade metals while completely retaining the original mechanical design of the standard Type 99 rifle. Testing revealed that, despite the use of “inferior” raw materials, the weapon remained highly reliable: it could withstand over 30,000 rounds, and its accuracy showed virtually no decline even after 5,000 shots. Nevertheless, the commission recommended returning to high-quality metals for future production, viewing this variant only as a temporary substitute.

Type 99 “Special” Rifle (Navy) — known in the West as the “Naval Special,” this model was created for the Imperial Japanese Navy as an extremely simplified surrogate. Its most defining feature was a receiver made of malleable cast iron, which allowed it to be manufactured even by factories that previously only produced training rifles. Because cast iron cannot withstand the pressure of a rifle cartridge, designers had to radically alter the locking mechanism, moving the locking lugs from the receiver directly onto the barrel. Visually, the rifle was characterized by a crude finish, the omission of the cleaning rod and dust cover, and the use of black paint instead of traditional bluing.

Type 99 “Special” Rifle (Navy).

While the earlier Type 97 sniper rifle was based on the Type 38 infantry rifle, the Type 99 Sniper Rifle and the Type 99 Short Sniper Rifle were developed using the Type 99 rifle series (long and short variants respectively) as their base. These rifles were equipped with a sniper scope for precision aiming. The bolt handle was slightly modified in shape, and a scope mount was added to the receiver; otherwise, the construction remained identical to the standard infantry rifles.

Type 99 short sniper rifle.

The length difference between the long and short sniper variants was 140 mm. Additionally, the sling swivels were located on the bottom for the long version and on the left side for the short version.

Type 97 2.5x optical sight.

Testing and Evaluation (1941–1942):

• May 1941: Following the completion of the prototype scope, vibration durability and accuracy tests were conducted at the Futtsu range using the Type 99 short rifle. The results showed that the scopes possessed sufficient durability for live firing, and accuracy was approximately 20% better than with iron sights.
• June 1941: Prototype rifles were submitted to the Infantry School for shooting exercises at the Takigahara range to test their effectiveness against field targets, though no definitive conclusion was reached at that time.
• September 1941: Field tests were conducted at the Sekiyama range with snipers dispatched from the Cavalry School. These tests compared rifles equipped with 4x scopes against those with 2.5x scopes. The 4x scope was found to be significantly more advantageous, with hit rates at distances over 600 meters being approximately 1.5 to 2 times higher.
• Early 1942: Between February and March, the rifles underwent practical service trials at the Infantry School. They were judged suitable for service after minor adjustments were made to the scope mounting position for better handling.

Type 99 4x optical sight.

Three variants of optical sights were intended for the Type 99 sniper rifle. A total of 1,000 units (two batches of 500 units each in 1941–1942) of the Type 99 sniper rifles produced by the Kokura Arsenal featured 2.5х10° optical sights with a new reticle designed for the ballistics of the 7.7mm Type 99 cartridge (7.7х58 mm).

Type 99 4x optical sight.

Specification	Type 99 Long Rifle	Type 99 Short Rifle	Type 99 Sniper Rifle (Long)	Type 99 Short Sniper Rifle
Overall Length	1258 mm	1118 mm	1258 mm	1118 mm
Length w/ Bayonet	1642 mm	1502 mm	1642 mm	1502 mm
Weight	4100 g	3800 g	4100 g	3730 g
Weight w/ Bayonet	4570 g	4270 g	4930 g	4790 g
Muzzle Velocity	740 m/s	730 m/s	740 m/s	730 m/s
Sighting Range	3400 m	3400 m	—	3400 m

A Type 99 short rifle equipped with a Type 99 light machine gun bipod was spotted in a private collection. Unfortunately, it is impossible to determine whether this weapon is an original World War II modification or a modern fake.

Type 99 short rifle equipped with a Type 99 light machine gun bipod.

Rifles for Paratrooper

The German Wehrmacht developed two experimental versions of the Kar98k for paratroopers (Fallschirmjäger):

• Kar98/42: A “take-down” model that separated at the receiver/barrel junction.
• V39 and G33/40: Models featuring a folding wooden stock. While these were high-quality designs, they never reached full-scale mass production.

The Imperial Japanese Army attempted to copy these German mechanisms:

• Type 100: Based on the Type 99 short rifle, it copied the Kar98/42 take-down system. It was abandoned because Japanese industry couldn’t mass-produce the high-precision screw threads required.

Type 100 prototype rifle.

Type 100 rifle.

• Type 1: Based on the Type 38 carbine, it copied the folding stock of the G33/40. It remained a prototype due to the poor durability of the hinge.

Type 1 rifle.

The eventual success of the Japanese paratrooper rifle came from a different experimental path:

• Experimental Type 99 (Tera): This model simplified the take-down system by using a wedge-and-screw locking mechanism instead of complex threads. It also featured a folding spike bayonet from the Type 44 carbine.
• Legacy: Only about seven units were produced by the Nagoya Arsenal. With minor adjustments—such as fixing the wedge direction and making the bayonet standard—this design directly evolved into the Type 2 Rifle, which finally entered mass production for Japanese airborne forces.

From top to bottom: Type 100, Type 99 (Tera), Type 2.

Specification	Type 2
Caliber	7.7 mm
Length	1118 mm
Weight	4035 g
Muzzle velocity	720 m/s
Magazine capacity	5 rounds
Bullet weight	11.8 g

There is also conflicting information in Japanese sources regarding the production of late-war Type 99 paratrooper rifles. The Type 99 rifle (Airborne) was established for exactly the same purpose as the Type 2 rifle. While the Type 2 was adopted in 1942 and saw limited practical use, its production was discontinued by 1944. In its place, the Type 99 rifle (Airborne) was officially adopted in October 1943. This shift occurred because the manufacturing process for the Type 2 was too labor-intensive. By converting the standard Type 99—which was already optimized for mass production—the military aimed to rapidly increase the supply of rifles specialized for paratrooper units.

Type 02/45 Rifle

Late in the war, an unknown number of rifles were assembled using Type 35 rifle receivers and bolts, 6.5mm rifle or (rarely) machine gun barrels, and training rifle stocks and other parts. The Type 35 rifle was adopted by the Japanese Navy in 1902 and manufactured in small numbers. The actions used for the Type 02/45 rifles ap-parently were left over from that period of manufacture and had characters for “35 Year Type” and the imperial chrysanthemum on the top of the receiver. The type designation “02/45” is a creation of collectors to reflect the 1902 adoption of the action and the presumed 1945 assembly of these rifles.

Type 02/45 Rifle.

Simple Rifles of 7.7 mm and 8 mm caliber

An attempt was made to create a very simple rifle firing standard 7.7mm cartridges. The barrel length was 50 cm, and the design was so simple that it, along with other parts, could be manufactured on a standard lathe. It was a single-shot bolt-action rifle. This weapon was intended to equip front-line defense troops.

Simple 7.7 mm rifle.

However, since the cartridges proved to be too powerful, it was decided to make the rifle shorter and use standard 8mm Type 14 pistol cartridges. This version proved to be much more successful.

Simple 8 mm rifles.

National Rifle

Designed for the defense of the nation and to equip volunteer forces, the National Rifle was a type of weapon that could be manufactured at any small factory or blacksmith shop. The design was simple, featuring a barrel formed from a common piece of pipe with a 13 mm diameter. It used a load of 3 to 5 grams of black powder, while the projectile was created by cutting an ordinary metal rod into sections approximately 15 mm long. The mechanism utilized an S-shaped spring-loaded percussion lock to strike a primer placed in a recess at the top of the breech.

American soldiers examine a National Rifle.

[_DELAVR]

AUTOMATIC AND SEMI-AUTOMATIC RIFLES

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AUTOMATIC AND SEMI-AUTOMATIC RIFLES

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Hino-Nambu Self-Loading Rifle

​The development of individual automatic weapons in Japan at the beginning of the 20th century was initiated under the direct influence of the combat effectiveness of machine guns demonstrated during the Russo-Japanese War. By 1909, Major Kijirō Nambu and Captain Kumazō Hino introduced a “self-firing rifle” project, which was positioned as a simplified and lightweight version of a machine gun system intended for a single soldier to carry and use directly within infantry charging lines. Foreign military press of the era indicated that Hino constructed this weapon by profoundly modernizing a “Danish pattern”—likely the Madsen system—achieving a rate of fire of approximately 100 rounds per minute.

​Despite successful demonstrations of prototypes in the presence of the Emperor and keen interest from foreign military attachés in 1910, the refinement of the system for mass production faced serious difficulties. It was not until 1921 that Lieutenant Colonel Hino presented an updated version of the rifle to the General Staff, which he claimed featured a 25-round magazine and surpassed contemporary European counterparts in reliability. However, despite ambitious claims regarding the ability to maintain rapid fire without the need for re-aiming, the system never saw widespread adoption within the Japanese Army.

Kayaba Self-Loading Rifle

In the early 1930s, Japanese inventor Shiro Kayaba, residing in the Shiba district of Tokyo, proposed a project for the deep modernization of the standard Arisaka Type 38 bolt-action rifle. The official patent application was filed on December 17, 1931, and the document was published under number 3136 on June 13, 1932. In the patent classification of that era, the development was categorized under “Machine Guns”.

Patent drawing of the Kayaba rifle.

Kayaba’s technical concept focused on converting the bolt-action rifle into a self-loading weapon while retaining the barrel, stock, and buttplate of the original Arisaka. The modernization involved replacing the bolt action with a new assembly capable of automatically cycling the opening and closing of the bolt, ejecting spent casings, and chambering new rounds. Analysis of the drawings reveals a gas-operated system featuring a gas rod located on the right side of the barrel, a layout remarkably similar to the Italian Cei-Rigotti rifle.

Artistic representation of the Kayaba rifle.

The patent places particular emphasis on safety and the reliability of the firing cycle. The trigger mechanism was designed with a safety lever functionally linked to the bolt movement, which blocked the sear to prevent a discharge until the bolt reached its fully locked position. Furthermore, the mechanism was strictly designed for semi-automatic fire; a specific disconnector intercepted the striker after each shot, even if the trigger remained depressed, thereby ensuring reliable operation and preventing uncontrolled automatic fire.

Patent drawing of the Kayaba rifle.

Nambu Self-Loading Rifle

Kijiro Nambu is said to have conceived and designed an automatic rifle as early as the late Taisho era, prior to establishing the Nambu Rifle Manufacturing Plant. From the beginning, he utilized a gas-operated system, a principle that remained consistent across all his subsequent automatic rifle designs.

In 1932 (the 7th year of the Showa era), when the Army Technical Headquarters officially began developing an automatic rifle, the Nambu plant submitted two types of prototypes to the 1st Technical Research Institute.

• Ammunition: The rifle was chambered for the 6.5mm Type 38 cartridge.
• Magazine: It featured a 10-round detachable box magazine.
• Operating Principle: The system used gas pressure to drive a piston back, which rotated the bolt a quarter-turn to unlock it.

The prototypes underwent firing tests at the Tokyo Arsenal and endurance tests in the extreme cold of Manchuria. Following rigorous trials involving immersion in water and mud, several refinements were made:

• A dust cover was added to the ejection port.
• To improve heat dissipation, a pure aluminum sleeve was fitted to the barrel.
• Ventilation ports were added to the handguard and the upper receiver.

Despite a solid basic design, the rifle suffered from a critical safety flaw: the hammer could fall and ignite the cartridge before the bolt was fully locked. In 1934 (the 9th year of the Showa era), following repeated accidents during testing at the Tokyo Arsenal that resulted in injuries to shooters from rearward-blown breech components, Nambu decided to withdraw from the Army’s automatic rifle development program.

Sketch of the Nambu automatic rifle by Taguchi Sadamitsu, who participated in the development of the rifle.

Even after withdrawing from the official competition, Nambu continued to refine the design independently:

• Purely Japanese Design: Unlike the competitors from the Tokyo Arsenal or Nippon Tokushu Ko (Japan Special Steel), which were based on the American Pedersen system, Nambu’s rifle was a purely original Japanese design.
• Record Low Weight: Through further development, the weight was reduced to 3.8 kg. For comparison, standard automatic rifles of that era typically weighed around 4.5 kg.

The Early Self-Loading Rifle of Saburo Watanabe (Prototype №1)

In 1931, the Nippon Special Steel Company, acting on a private initiative, presented a prototype self-loading rifle chambered for the 6.5×50SR cartridge to the Technical Department of the Imperial Japanese Army Headquarters. The development was conducted by an engineering team under the leadership of the company’s Vice President, Saburo Watanabe. A primary objective of the project was the creation of an original reloading mechanism that avoided the use of technical solutions protected by existing domestic or foreign patents.

Patent drawing of the Saburo Watanabe rifle.

The technical foundation of the rifle was based on a delayed blowback principle utilizing recoil energy. The delay in bolt opening and the cocking of the firing pin were achieved through a complex system of levers and oscillating pendulum-flywheels. This mechanical arrangement provided a “shockless” operating cycle, as the pendulums dampened the movement of the bolt group in both its forward and rearward positions. The spring system consisted of a top tension spring to facilitate the initial displacement of the bolt and two lower return springs mounted on guide rods.

Patent drawing of the Saburo Watanabe rifle.

The rifle’s feed system utilized a fixed magazine loaded with a specialized en-bloc clip designed by Watanabe. This clip featured a triple-row configuration with a capacity of 15 rounds. Ammunition was fed via a spring-loaded lever with a U-shaped follower. The design incorporated a bolt catch that activated upon the exhaustion of the clip or during manual manipulation; the bolt was released by pressing a button located on the right side of the receiver.

Patent drawing of the Saburo Watanabe rifle.

The legal priority of the design was established through a series of patents. In December 1931, Saburo Watanabe was granted Japanese Patent for the cartridge clip design, followed in March 1932 by Patent, which detailed the principles of the rifle’s automatic action. The supporting documentation provided an exhaustive description of the interaction between the lever mechanisms and the pendulum stabilizers.

Patent drawing of the Saburo Watanabe rifle.

Despite the uniqueness of the engineering solutions, the total number of individual components in the prototype reached 182. The excessive complexity of the mechanisms rendered the mass production of this model as a standard military firearm technologically and economically unfeasible. While the 1931 project did not undergo further modernization, it served as the technological basis for subsequent Nippon Special Steel models introduced in 1932.

Patent drawing of the Saburo Watanabe rifle.

The Saburo Watanabe Self-Loading Rifle (Prototype №2 / 1932 Model)

In 1932, the Nippon Special Steel Company introduced its second prototype self-loading rifle. Conceptually, this model was not a continuation of the 1931 project but a distinct design. Designated in Japanese literature as the “Type Hei Early Model,” it became the most widely recognized version internationally due to patent filings in the United States, Great Britain, and France. This rifle established the foundation for two subsequent development paths: the standard army automatic rifle program and the experimental “ultra-lightweight” automatic rifle of 1935.

Patent drawing of the Saburo Watanabe rifle.

The design represented a synthesis of several established mechanical systems:

• Locking Mechanism: The rifle utilized a toggle-lock (knee-joint) system, structurally similar to the design developed by John Pedersen in 1927.
• Spring Mechanism: The implementation of the main spring was influenced by the solutions of the Austrian designer Andreas Schwarzlose (1902).
• Operating Principle: Unlike the first model, this version employed a gas-operated system with a short-stroke piston located beneath the barrel.

Patent drawing of the Saburo Watanabe rifle.

Chambered for the standard Japanese 6.5×50SR cartridge, the rifle featured several notable mechanical characteristics:

• Gas Regulator: A three-position regulator allowed for the adjustment of gas volume based on climatic conditions: maximum for low temperatures (winter), medium for temperate climates, and minimum for dry environments.
• Inverted Piston Movement: Upon firing, the gas piston moved forward to unlock the action. This movement pushed the bolt carrier, which in turn forced the toggle levers upward out of their “dead center” (locked) position, initiating the unlocking of the bolt.
• Multifunctional Spring: A single spring served two purposes: acting as a return spring for the bolt carrier and gas rod assembly, and functioning as a buffer for the bolt during its final stage of rearward travel.
• Feed System and Bolt Catch: The rifle featured a 10-round fixed double-stack magazine, loaded from the top using two standard five-round stripper clips. Upon firing the final round, the mechanism engaged a bolt catch, locking the toggle action open for rapid reloading.

The Saburo Watanabe Self-Loading Rifle (Prototype №2 / 1932 Model). The rifle participated in the first stage of the automatic rifle trials in 1932, alongside the Type Ko and Type Otsu.

The Saburo Watanabe Self-Loading Rifle (Prototype №3)

In this design, Saburo Watanabe sought to create a simplified construction suitable for mass production and easy adoption by personnel already familiar with the standard Arisaka Type 38. Despite its intended simplicity, the project featured several unconventional engineering solutions regarding its internal layout and operating cycle.

Patent drawing of the Saburo Watanabe rifle.

The primary objective of the project was manufacturability. Unlike previous models, Prototype No. 3 utilized a simplified locking scheme and a gas-operated action with a long-stroke piston. Its most distinctive feature was the architecture of the receiver:

• Internal Partitioning: The receiver was divided into two distinct sections: the forward section for the bolt group and the rear section for the magazine.
• Rear-Mounted Magazine: Unusually, the magazine was positioned behind the bolt in the breech section of the rifle. Feeding was accomplished via a specialized 8-round en-bloc clip (6.5×50SR).
• Loading Procedure: To load the weapon, the operator opened the magazine cover upward in a clockwise direction. It is hypothesized that the empty clip was automatically ejected upon opening the cover, similar to the function of the M1 Garand.

Patent drawing of the Saburo Watanabe rifle.

The rifle featured a highly non-standard mechanical algorithm, necessitated by the rear-mounted magazine and the requirement to fire from a closed bolt:

1. Charging the Weapon: To ready the rifle, the operator moved the charging handle forward. During this motion, the bolt carrier moved forward (with the gas piston rod extending slightly from the handguard), while the bolt itself moved rearward to open the ejection port and catch a round from the clip.
2. Chambering and Locking: Upon releasing the handle, the bolt moved forward to chamber the round and lock into place. Simultaneously, the bolt carrier returned to its original (rearward) position.
3. Mechanical Principle: This configuration effectively implemented an early form of balanced-action mechanics. Although the bolt carrier remained in the rearward position when ready to fire, the bolt itself was closed and locked in the forward position, ensuring accuracy and safety.

Patent application, titled “Improved Automatic Rifle,” was filed on June 3, 1932. This prototype demonstrated Watanabe’s attempt to adapt automatic small arms to the ergonomics and industrial capabilities of the era. However, due to the inherent complexity of its specialized en-bloc feed system and unconventional reciprocal movement, Model No. 3 remained in the experimental stage and did not proceed to mass production.

Saburo Watanabe Self-Loading Rifle (Prototype №3), preserved to this day without the top cover.

The Type Ko, Type Otsu and Type Hei Self-loading rifles

The introduction of semi-automatic systems based on John Pedersen’s patents into the production program of the Tokyo Artillery Arsenal was driven by active marketing of the design and the developer’s influence on General Tomoyoshi Yoshida. Between 1930 and 1932, the Japanese military department acquired the full patent documentation, viewing the system as a technologically mature solution.

Type Ko rifle prototype.

During the adaptation process led by Hayahiko Mihara, the Type Ko rifle was redesigned to chamber the standard Japanese 6.5 mm cartridge. The original en-bloc clip loading system was replaced by a 10-round rotary magazine fed by standard stripper clips. From 1935 onwards, the design incorporated mounts on the side of the receiver for the installation of Type 5 optical sights.

Type Ko Carbine with Type 44 Bayonet.

The 1936 trials revealed critical operational unreliability of the Type Ko rifle due to systematic shell extraction failures. The technical cause was the incompatibility of the standard Arisaka chamber with the Pedersen action, which required the use of wax-coated cartridges. Administrative barriers and the leadership’s disregard for Engineer Kawamura’s expert recommendations prevented the rectification of these defects. Consequently, total production was limited to 24 units before the project was terminated.

The final versions of the Type Ko long were equipped with bipods and Type 5 optical sights.

More photos

Type Ko Carbine with Type 44 Bayonet

Type Ko short.

Type Ko short.

Type Ko long.

Type Ko long.

The history of the Japanese self-loading rifle known as Type Otsu began with the capture of trophy Czechoslovak ZH-29 rifles in China. The Northeastern Army of the Republic of China had previously purchased over 500 units of this weapon and planned to establish licensed production in Mukden; however, the Japanese occupation of Manchuria in 1931 disrupted these plans. The study of these Czechoslovak specimens gave rise to a new direction in Japanese development, designated as the Type Otsu.

ZH-29 rifle captured by the Japanese.

The development of this model was carried out by the Tokyo Gas Electric (TGE) company under the general supervision of Kijirō Nambu. Structurally, the Type Otsu was an almost exact copy of the Czechoslovak ZH-29, modified to chamber the standard Japanese 6.5x50mm SR cartridge. For the competitive trials of 1935, only eight experimental units were produced in two versions—long and short. Notably, the long version was equipped with mounts for the Type 5 optical sight.

Type Otsu long version with a 5-round magazine.

The trial results proved to be highly unsatisfactory, as the rifle failed the tests due to poor accuracy and fatal reliability issues. Improper headspace dimensions caused frequent swelling and rupturing of cartridge cases. One incident involved a discharge with an unlocked bolt, resulting in the shooter being injured by shell fragments. Furthermore, the minimal tolerances within the mechanism made the weapon extremely sensitive to dust and dirt.

Mounting slot for the Type 5 optical sight on the Type Otsu long version.

Ultimately, in 1936, the army commission officially removed the Type Otsu from further testing. The rifle was deemed too complex for mass production and failed to meet the reliability standards required for combat conditions, effectively ending the development of this particular branch of Japanese small arms.

Type Otsu short.

The Type Hei rifle, developed by Nippon Special Steel under the leadership of Dr. Masaya Kawamura, underwent a long evolutionary path from its first 1932 prototypes to the final production samples. A key moment in the system’s development was the transition from a fixed magazine to detachable box magazines with 5 and 10-round capacities. For improved operation, a safety for the magazine release button was added, and a T-shaped slot was retained in the bolt, allowing the rifle to be loaded using standard clips similar to Lee-Enfield rifles. Additionally, the return spring was moved from the rear of the receiver to a position forward under the handguard.

Early Type Hei rifle with a 10-round magazine beside it. The rifle lacks a magazine release button and a front sight protector.

During the 1935 trials, it was discovered that the rifle’s accuracy was unsatisfactory due to barrel overheating, which caused the bullets to drift. In response, designers introduced a series of modifications: increasing the barrel wall thickness to match the Type 38 rifle, changing the gas cylinder mounting methods, and experimenting with barrel length. A characteristic cutout for mounting the Type 5 optical sight appeared on the left side of the receiver, which was protected by a special plug when not in use.

Modernized Type Hei rifle.

Significant modernization of the Type Hei occurred during the third trials in March 1936. Three new units received receiver modifications to improve accuracy, and the stock and handguard were integrated into a single-piece stock. The trigger mechanism became two-stage. For older samples, the breech end of the barrel was thickened to reduce vibrations during firing, and a deep hole (10 mm in diameter and 80 mm deep) was drilled into the muzzle end. These measures significantly increased the reliability of the automation and reduced the number of malfunctions, although accuracy still required improvement.

Top: Late Type Ko short version. Bottom: Late Type Hei short version.

The final “late” version of the Type Hei emerged as part of the fourth experimental batch ordered in June 1936. This version was produced in both long and short variants. These rifles, delivered by early 1937, represented the most advanced version of the system: they were standardly equipped with mounts for Type 5 optical sights and easily detachable bipods. Despite successfully passing winter tests and field trials at Mount Myoko, the project was frozen in 1938. The enactment of the National Mobilization Law forced Japan to focus on the production of the proven Type 38 rifles, marking the end of the Type Hei’s development history.

Late Type Hei long rifle.

More photos

Late Type Hei long rifle.

Early Type Hei rifle with a 5-round magazine.

Mounting slot for an optical sight on the left side of the receiver on an early Type Hei rifle.

Enclosed mounting slot for an optical sight.

Late-model Type Hei short rifle with bipods.

Specification	Version	Type Ko	Type Otsu	Type Hei (Late)
Total Length	Long	1160 mm	1180 mm	1160 mm
Total Length	Short	1060 mm	1080 mm	1060 mm
Barrel Length	Long	673 mm	650 mm	690 mm
Barrel Length	Short	573 mm	550 mm	590 mm
Weight (w/o bayonet & magazine)	Long	—	4.255 kg	4.147 kg
Weight (w/o bayonet & magazine)	Short	4.250 kg	4.030 kg	3.785 kg
Magazine Weight	10-round	—	190 g	226 g
Magazine Weight	5-round	—	145 g	126 g
Muzzle Velocity	Short	735 m/s	725 m/s	740 m/s
Number of Parts		117	88	98

Saburo Watanabe’s ultra-light machine gun

In 1938, Nippon Special Steel developed an experimental ultra-light machine gun (effectively an automatic rifle) based on the late-model Type Hei rifle. The core concept was to create a mobile weapon weighing only 5.6 kg, which was nearly half the weight of the standard Type 11 and Type 96 light machine guns. It was envisioned that this lightness would allow an infantry squad to be equipped with two automatic units instead of one.

Ultra-light machine gun with a 30-round magazine.

The weapon retained the gas-operated system with a toggle-lock (crank) mechanism. It featured curved box magazines with 20 or 30-round capacities, a cooling radiator on the barrel, and a drum-type aperture sight. The machine gun supported both semi-automatic and fully automatic fire, included a bayonet lug, and used folding bipods, making it a versatile tool for close-quarters combat and anti-aircraft fire.

Ultra-light machine gun with a 20-round magazine and a shield.

Trials conducted in June 1938 at the Futtsu Proving Ground revealed critical flaws:

• Low Reliability: Due to the complexity and fragility of the toggle mechanism, parts broke very early (as early as the 246th shot), leading to the premature termination of the tests.
• Poor Ergonomics: The bottom-mounted magazine made firing from behind cover difficult, and spent cartridges were ejected upward. A functional bolt hold-open (last round bolt hold) was virtually non-existent (the bolt closed when the magazine was removed).
• Low Accuracy: The rate of fire was excessive (720 rounds/min). During burst fire at 300 meters, only the first bullet would typically hit a 4×4 meter target.
• Production Complexity: The design required a high amount of specialized patented alloys and featured complex part shapes, which was unacceptable for wartime mass production.

Disassembled ultra-light machine gun. Note the slot on the left side of the receiver; it can be assumed that it was designed for an optical sight.

The commission deemed the prototype unsuccessful, and the project was closed. Notably, existing photographs show a mounting slot on the left side of the receiver, presumably intended for the Type 97 optical sight. By the time these machine gun trials began, the Type 97 sight had already been officially adopted by the Japanese Army for a year.

Specification	Saburo Watanabe’s ultra-light machine gun
Caliber	6.5 mm
Rate of Fire	720 rpm
Muzzle Velocity	730 m/s
Overall Length (w/o bayonet)	1007 mm
Barrel Length	528 mm / 526 mm*
Weight (with bipod, w/o bayonet)	5.400 kg / 5.650 kg*
Empty Magazine Weight 20 / 30 rounds	0.402 kg / 0.533 kg
Bipod Weight	0.382 kg / 0.632 kg*
Bipod Height	250 mm / 306 mm*

*Note: Values refer to Model No. 2.

Kokura Arsenal Self-Loading Rifle 1941

The 1941 Kokura Arsenal rifle is a short-recoil operated rifle constructed using a large number of components from the Type 99 rifle. For example, the rifle features a 5-round (7.7×58mm Arisaka) fixed magazine that is structurally identical to that of the Type 99 rifle.

1941 Kokura Arsenal rifle

e rifle is equipped with rails for mounting a standard Type 99 optical sight, offset to the left of the loading and ejection port.

1941 Kokura Arsenal rifle

More photos

1941 Kokura Arsenal rifle

1941 Kokura Arsenal rifle

1941 Kokura Arsenal rifle

1941 Kokura Arsenal rifle

1941 Kokura Arsenal rifle

Self-Loading Rifle Contest 1942–1943

Between 1942 and 1943, the research team at Kokura Arsenal’s 2nd Plant and the 1st Department of the 1st Army Research Institute in Tokyo submitted competing designs for evaluation. While details of the program remain scarce, the designs from the 1st Department featured a gas-operated system with a 5-round magazine. In contrast, the Kokura Arsenal prototypes utilized a short-recoil locking system and a 5-round magazine; in this design, the barrel and mechanism recoil approximately 1/8 of an inch before the bolt begins to rotate and unlock. Testing of both types, in both their initial and improved configurations, yielded unsatisfactory results. Furthermore, military officials concluded that neither private industry nor military arsenals possessed the production capacity or skilled personnel required to mass-produce a weapon as complex as a semi-automatic rifle. Consequently, the program was terminated in 1943.

The semi-automatic rifle development program was reinstated in 1941. 7.7mm. caliber rifles developed during the 1941-1943 period were (from top-to-bottom): (1) Rifle Plan №1, from the Tokyo Research Center; (2) Rifle Plan №2, from the Tokyo Research Center; (3) Rifle Plan №1, from the Experimental Section of Kokura Arsenal; (4) Rifle Plan №2, from the Experimental Section of Kokura Arsenal.

Modernization of Type 38 and Type 99 — The Tetsutaro Project

In 1941, inventor Tetsutaro proposed a project to convert the standard Type 38 into a self-loading rifle. Key features included:

• Modular Assembly: The barrel and receiver were attached to the stock in a unique way: a hook at the front caught a transverse axis, while a spring-loaded piston secured the rear. This allowed for quick field stripping without tools.
• Action: The design utilized a toggle-lock mechanism (similar to the Pedersen system). The levers were actuated by short recoil: upon firing, lugs on the toggle struck stationary lugs on the stock’s piston, initiating the folding of the levers and unlocking the bolt.
• Trigger and Magazine: The trigger acted on a sear lever that released the cocked striker’s cam. The magazine featured a unique spiral guide system, with rounds moved by a lever-type follower powered by a coiled spring. When empty, the follower blocked the bolt.
• Safety Features: It included a trigger block and a specific “recoil stop” to rigidly lock the barrel and receiver to the stock when using a bayonet, preventing accidental bolt opening from mechanical shock.

Drawing of a modified Arisaka Type 38 rifle from the Tetsutaro patent.

More photos

Drawing of a modified Arisaka Type 38 rifle from the Tetsutaro patent.

Drawing of a modified Arisaka Type 38 rifle from the Tetsutaro patent.

Drawing of a modified Arisaka Type 38 rifle from the Tetsutaro patent.

Drawing of a modified Arisaka Type 38 rifle from the Tetsutaro patent.

Drawing of a modified Arisaka Type 38 rifle from the Tetsutaro patent.

Drawing of a modified Arisaka Type 38 rifle from the Tetsutaro patent.

Drawing of a modified Arisaka Type 38 rifle from the Tetsutaro patent.

Drawing of a modified Arisaka Type 38 rifle from the Tetsutaro patent.

Drawing of a modified Arisaka Type 38 rifle from the Tetsutaro patent.

Drawing of a modified Arisaka Type 38 rifle from the Tetsutaro patent.

In 1942, the concept shifted toward improved reliability and the 7.7 mm caliber:

• Gas-Operated System: Instead of barrel recoil, a cylindrical gas chamber was introduced at the muzzle. Powder gases acted on a piston and rod to move an L-shaped lever, which forced the toggle mechanism to fold.
• Simplified Design: The quick-strip system and the complex spiral magazine were abandoned.
• New Magazine: A hinged bottom floorplate was added for easy cleaning. Feeding was performed by a follower lever with a powerful coil spring on the hinge axis, supplemented by a leaf spring to keep the follower level.

Drawing of a modified Arisaka Type 99 rifle from the Tetsutaro patent. Standard magazine.

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Drawing of a modified Arisaka Type 99 rifle from the Tetsutaro patent. Standard magazine.

Drawing of a modified Arisaka Type 99 rifle from the Tetsutaro patent. New magazine.

Type 4 Self-Loading Rifle

The first American self-loading rifles, specifically the M1 Garand (1936 model) and the M1941 Johnson in .30-06 caliber, officially fell into Japanese hands during the Battle of Guadalcanal between August 1942 and February 1943. While the initial U.S. Marine landings on August 7, 1942, involved troops primarily armed with bolt-action M1903 Springfield rifles and a limited number of Johnson rifles, the M1 Garand began arriving in force with subsequent reinforcements throughout September 1942.

During the Japanese evacuation of Guadalcanal (Operation Ke) in early 1943, the military managed to rescue not only over 10,000 soldiers but also a variety of captured American equipment. Among the technical samples brought back were radios, ammunition, machine guns, and several M1 Garand rifles. These captured rifles, reportedly brought back by the 5th Battalion of the Yokosuka Special Naval Landing Force (Rikusentai), quickly drew the attention of specialists at the Naval Arsenal.

Type 4 prototype.

Japanese experts noted the M1 Garand’s exceptional reliability and performance in dusty or fouled conditions. However, they deemed the American en-bloc clip system too complex for mass production under current domestic constraints. Consequently, the naval arsenal decided to develop a localized version, aiming for simplification and unification with Japanese logistics. This effort resulted in the Type 4 rifle (1944 model) produced at the Yokosuka Naval Arsenal.

Type 4 rifle.

The Type 4 rifle featured several significant modifications from the original American design. The chrome-lined barrel was shortened and rechambered for the standard Japanese 7.7mm Type 99 cartridge. The complex 8-round clip system was replaced by a 10-round fixed internal magazine, which was loaded from the top using two standard 5-round stripper clips. Additional changes included a simplified aperture sight, a mounting lug for the Type 30 bayonet, and left-side sling swivels. Unlike the high-quality parkerized finish of the American M1, the Japanese versions exhibited rough machining marks and a less durable oxidized finish.

There is also information regarding the development of folding-stock versions of the Type 4, and a late-war Navy armament handbook mentions the possibility of introducing sniper fire. However, no sniper version of the Type 4 or a model with a folding stock has ever been found.

Specification	Type 4
Caliber	7.7 mm
Weight	4.097 kg
Overall Length	1.076 m
Muzzle Velocity	689 m/s

[_DELAVR]

SHOTGUNS

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SHOTGUNS

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Murata Shotguns

Type 13 and Type 18 Murata rifles were converted into smoothbore shotguns by private gunmaking companies in Japan. These conversions resulted in single-shot, mechanically simple shotguns.

Murata shotguns.

The standard weights for large-bore Murata shotguns are as follows: approximately 5.625 kg for 8-gauge models and 3.75 kg for 10-gauge models. The 12, 16, 20, and 24-gauge versions weigh between 2.8 and 2.9 kg, depending on the gauge, barrel length, and the type of wood used for the stock (beech or walnut).

Murata shotgun.

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Murata shotgun.

Murata shotgun.

Murata shotgun.

Murata shotgun.

Shotguns for the Imperial Japanese Navy

In the Navy, shotguns were used instead of rifles for close-quarters combat in the jungle. For this purpose, approximately 50,000 12-gauge (18 mm) shotguns were requisitioned from members of the All-Japan Hunters’ Association, including single-shot, double-barreled, and multi-shot (repeating) models. Many of these shotguns were equipped with bayonet lugs.

Australian soldiers inspecting Japanese shotguns.

The ammunition was independently developed by the Navy: the shell was loaded with 12 steel balls, each 6.5 mm in diameter. The power of the shot was sufficient to penetrate a one-inch (2.54 cm) pine board at a range of 50 meters.

Japanese Navy Shotgun.

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Japanese Navy Shotgun.

Japanese Navy Shotgun.

Japanese Navy Shotgun.

[_DELAVR]

PISTOLS

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PISTOLS

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Smith & Wesson Revolvers

Since the beginning of the Meiji era, the Imperial Japanese Army adopted American-made Smith & Wesson revolvers, issuing them to the Imperial Guard Cavalry, transport troops, and non-commissioned officers (NCOs) of field and mountain artillery batteries. They were also issued to the NCOs and enlisted men of the Military Police (Gendarmerie), established in the 1881. The “Russian Model” was designated as the No. 1 Model Revolver, while the “American Model” was called the No. 2 Model Revolver. Smith & Wesson revolvers were also adopted by the Navy; the 1886 manual “Naval Revolver Drills” includes instructions for the No. 1 Model.

The bottom photograph shows the No. 2 Model Revolver, officially known as the S&W Model No. 3 .44 cal Single Action (New Model). The top photograph shows the same type of weapon, the Russian Model, which was referred to as the No. 1 Model Revolver.

Specification	Smith & Wesson Revolver
Caliber	10.66 mm
Overall Length	347 mm
Weight	1210 g
Capacity	6 rounds
Bullet Weight	13.81 g

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Japanese Smith & Wesson revolver.

Japanese Smith & Wesson revolver.

Type 26 Revolver

Until this point, the Japanese Army had relied entirely on American-made Smith & Wesson revolvers. However, this was contrary to the fundamental principle of weapon independence and resulted in economic losses. Consequently, plans were made to produce firearms domestically. Following research conducted at the Tokyo Artillery Arsenal starting around the 1888, a top-break six-shot revolver was designed. After testing by the Artillery Committee yielded favorable results, it was officially adopted on March 29, 1894, as the Type 26 Revolver.

Type 26 revolver.

At the time, the Type 26 was a state-of-the-art model. It featured a mechanism where a six-chamber cylinder rotated in connection with the firing mechanism, aligning the chambers sequentially with the barrel. The caliber was set at 9mm. By October 1896, a blank cartridge for the Type 26 — which had been under development since 1892 — was also completed.

Specification	Type 26 Revolver
Caliber	9 mm
Overall Length	229 mm
Weight	904 g
Muzzle Velocity	230 m/s
Capacity	6 rounds
Bullet Weight	9.8 g

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Type 26 revolver.

Type 26 revolver.

Type 41 Pistols

The development of Japanese automatic pistols began around 1899 with the study of foreign models, including the Parabellum system, and their subsequent field testing during the Boxer Rebellion. By 1902, technical analysis of designs by Bergmann, Borchardt, Mauser, and Browning provided the foundational data for creating domestic weapons intended to replace the obsolete Type 26 revolver. Under the leadership of Kijirō Nambu at the Tokyo Artillery Arsenal, two prototypes were developed: a “Large Model” for frontline units and a “Small Model” for officer self-defense.

Small Model pistol.

Between 1908 and 1910, the Large Model underwent official trials under the designation “Type 41 Automatic Pistol”. This system was produced in two primary variations: Ko and Otsu. The principal distinction between them lay in their accessories: the Ko variant was equipped with a wooden holster that doubled as a shoulder stock for firing at ranges of 300–400 meters, while the “Otsu” variant was supplied with a standard leather holster. Despite positive test results and the confirmation of the design’s originality, the official adoption of the Type 41 by the army was blocked by War Minister Terauchi due to budgetary constraints.

Large Model Ko pistol.

The technical differences between the Nambu models were dictated by their tactical roles and calibers. The Large Model utilized an 8mm cartridge and an 8-round magazine, providing an effective range of up to 100 meters. The Small Model featured a 7mm caliber, a 6-round magazine, and a total mass of 920 grams. A characteristic feature of both systems was the placement of the magazine within the grip and a short-recoil operation (approximately 5mm), where the bolt remained locked in the open position after the final round was fired. Although these pistols never achieved official status as the primary army sidearm, they were widely purchased by officers, utilized by the Imperial Japanese Navy, and exported to China.

Large Model Otsu pistol.

Specification	Nambu Large	Nambu Small Type
Caliber	8 mm	7 mm
Overall Length	229 mm	174 mm
Weight	945 g	548 g
Muzzle Velocity	315 m/s	280 m/s
Max Range	500 m	—
Capacity	8 rounds	6 rounds
Bullet Weight	6.6 g	3.65 g

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Small Model pistol.

Small Model pistol.

Large Model Ko pistol.

Large Model Ko pistol.

Large Model Ko pistol.

Hino-Komuro Pistol

The Hino system pistol, also classified in international historiography as the Hino-Komuro M1908, is a semi-automatic handgun based on the rare blow-forward operating principle. Developed by Japanese Lieutenant Kumazo Hino, the design is characterized by the absence of a moving slide or bolt; the receiver and firing pin remain static, while the cycling of the action is achieved through the longitudinal movement of the barrel under the influence of propellant gases and a recoil spring.

Early Hino-Komuro pistol.

The technical cycle of the action involves the barrel surging forward upon firing to extract the spent casing. Upon reaching its forward-most point, the barrel is driven backward by spring tension, chambering a new round from the magazine and impaling the primer against a fixed firing pin. Initial cocking requires the operator to manually pull the barrel forward until it is engaged by the sear. This mechanism is considered inherently unsafe: should the operator’s fingers slip during cocking, the barrel returns to its original position under spring pressure, resulting in an accidental discharge due to premature primer ignition.

In the manual for the Hino-Komuro pistol, mention was made of the Ko version, which featured the capability to utilize a wooden holster as a detachable shoulder stock.

The operational safety of the Hino system is further compromised by the absence of a trigger guard and the unconventional layout of its controls. Both the grip safety lever and the trigger are situated on the front strap of the grip. This configuration increases the risk of accidental discharge during high-stress handling, such as drawing the weapon from a holster. Furthermore, the design lacks an independent disconnector; improper trigger manipulation can consequently lead to uncontrolled automatic fire.

The Hino-Komuro pistols exhibit variations from series to series. Comparisons have been made between pistols with lengths of 256 mm and 237 mm.

Currently, extant and documented specimens are confirmed in .32 ACP and 8mm Nambu calibers, both featuring an 8-round magazine capacity. However, archival promotional brochures from the early 20th century stated that the manufacturer offered variants in a wide range of calibers, from 5mm to 8mm. In these specifications, magazine capacities reportedly varied from 8 to 15 rounds depending on the ammunition type. Despite its engineering uniqueness, total production reached only approximately 500 units, and manufacturing ceased by 1912.

Specification	7.65 mm Model (.32 ACP)	8 mm Nambu Model
Barrel Length	194 mm	217 mm
Total Length	237 to 256 mm	265 mm
Weight	680 g	907 g
Magazine Capacity	8 rounds	8 rounds

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Hino-Komuro pistol.

Hino-Komuro pistol.

Hino-Komuro pistol.

The most notable iteration of this handgun system is the 7.65 mm caliber specimen bearing serial number “32.” Although existing technical documentation is limited to low-quality photographic evidence, this specific unit represents a significant evolution of the original design. While there are hypotheses suggesting this firearm may have been modified in China, current expert consensus points toward a Japanese modification executed between 1939 and 1941.

Hino-Komuro №32 pistols.

The modification addressed several critical flaws inherent in the standard Hino-Komuro design through the following upgrades:

• Enhanced Safety System: A secondary manual lever safety was integrated into the design, resulting in a dual-safety configuration.
• Adjustable Firing Pin Mechanism: An adjustable firing pin assembly was introduced. It is theorized that this mechanism was intended to facilitate the safe unloading of the weapon, a procedure known to be hazardous in the base model.
• Refined Ergonomics: The ergonomics of the barrel were substantially modified, significantly improving the ease of the cocking process.

These engineering adjustments appear to successfully mitigate the primary operational deficiencies of the original platform. At present, specimen №32 is located in a Japanese repository.

Model Ko Pistol

he Type 26 revolver had already become obsolete by that time and was found to be ineffective for troops in Manchuria wearing winter uniforms. It had even reached the point where the Kempeitai (military police) of the Kwantung Army were being issued large Mauser-style military pistols.

In April of the 1921, the “Experimental Model Ko Automatic Pistol” was designed by the Technical Department as a revision to the Type 26 revolver, and an order was placed with the Tokyo Artillery Arsenal. Subsequently, numerous tests were conducted regarding rate of fire, accuracy, penetration, and durability. Following practical trials entrusted to the Infantry School, Cavalry School, and Field Artillery School, and after several modifications, the functional results were deemed favorable.

Model Ko pistol.

Ultimately, it was recognized as the replacement for the Type 26 revolver. However, at that time—though it was never realized—there were plans to arm infantry light machine gun sections with machine carbines. Because of this, the Experimental Model Ko Automatic Pistol was considered somewhat lacking in power and was also high in price, leading to the review being suspended once again.

Model Ko pistol.

Following these developments, a service pistol was finally established to replace the Type 26. Ultimately, the internal structure and functions followed the design of the Nambu-style Large Automatic Pistol. To make production as easy as possible, the Small Arms Manufactory of the Tokyo Arsenal carried out design prototypes, devising a way to manufacture many of the parts using a lathe.

Specification	Model Ko pistol
Caliber	8 mm
Overall Length	257 mm
Weight	1100 g
Muzzle Velocity	330 m/s
Max Range	300 m
Capacity	15 rounds
Bullet Weight	6.6 g

Type 14 Pistol

The development of the new pistol began with a set of stringent requirements: no shoulder stock, a magazine capacity of at least 8 rounds, and the ability to engage personnel at ranges up to 100 meters. The first five prototypes were completed in November 1922. However, in March 1923, while work was underway to improve the design, the prototypes and all documentation were destroyed in a fire caused by the Great Kanto Earthquake.

In 1924, testing resumed with new samples. Military schools held differing opinions: the infantry and cavalry deemed the weapon suitable, while the artillery corps found it too bulky. Ballistic tests showed an average muzzle velocity of 317 m/s and good accuracy, but also revealed reliability issues—frequent misfires and casing jams occurred, necessitating a redesign of several components.

Early (upper, Nagoya-Chigusa factory serial number 872 made in July 1927) and late (lower, Nagoya-Toriimatsu factory second series serial number 71847 made in June 1945) examples of the Type 14. Note smooth “slab” grip panels on the late production example, used beginning in November 1944.

During final trials in December 1924, the prototypes were split into two modifications: Model Ko and Model Otsu. Following additional tests in early 1925, it was decided that Model Otsu was better suited for mass production due to its simplified design. Consequently, on August 22, 1925, Model Otsu was officially adopted as the “Type 14 Pistol.”

Even after its adoption, the Type 14 underwent continuous modifications:

• ​1934: The diameter of the cocking knob (bolt ring) was increased, and the rear sight notch was widened.
• ​1938: The magazine floorplate material was changed to a different aluminum alloy to streamline production.
• ​1939 (Most Significant): The trigger guard was significantly enlarged, allowing soldiers to fire the weapon while wearing heavy winter gloves.

Specification	Type 14 Pistol
Caliber	8 mm
Overall Length	230 mm
Weight	890 g
Muzzle Velocity	334 m/s
Max Range	1600 m
Capacity	8 rounds
Bullet Weight	6.6 g

Pistol-Sword

In July 1921, the Army Technical Headquarters initiated a department plan to develop a sword integrated with a pistol, incorporating feedback from the Cavalry School to establish the following design requirements:

• Purpose: The pistol is intended for use while mounted, specifically for combat during breakthroughs or pursuits where a saber cannot be effectively used. It is also for self-defense for scouts and messengers.
• Design: A small, easy-to-handle automatic pistol is built into the hilt of the saber. Two prototypes were to be made: Ko, where the barrel and blade intersect at nearly a right angle, and Otsu, where the barrel and blade are nearly parallel.
• Pistol Characteristics: Utilize a short-recoil system with an 8mm caliber. Ammunition should be identical to those used in prototype automatic pistols whenever possible. The magazine must be easily detachable and replaceable even while the sword is drawn. Magazine capacity must be at least 8 rounds. A safety mechanism is mandatory, and the design must allow a rapid transition from a shooting posture to a slashing posture without releasing the grip.
• Sword Characteristics: Weight must be distributed for optimal balance in both thrusting and slashing. The blade length follows the Type 32 (Ko) saber. The standard weight of the weapon excluding the scabbard is 1.8 kg.
• Carriage: The sword is kept in a steel scabbard and always suspended on the right side of the saddle.
• Deadline: The target completion date for the first prototype was May 1922.

The pistol used for this project was the Nambu automatic pistol, which existed in “Large” and “Small” variants. Tests conducted by the Army Technical Evaluation Department starting in September 1907 yielded good results and proved its practicality. This led to a request from the cavalry to adopt the pistol, and the idea of integrating it with the saber emerged for carrying convenience.

In January 1922, following the approval of the design requirements, four prototypes were ordered from the Tokyo Artillery Arsenal. The project was officially authorized by the War Ministry and added to the “Second Weapon Research Policy” for cavalry equipment.

In June 1922, the Otsu prototype — consisting of a Type 32 saber equipped with a Small Nambu pistol—was completed. However, because the parallel alignment of the barrel and blade limited freedom of operation, research on this model was discontinued. Work then began on the Ko type. Design changes were made to use the Small Nambu ammunition, and the blade length was shortened from the original Type 32 (Ko) length of 835 mm to 780 mm.

In January 1923, one Ko prototype was finished. It proved difficult to handle as a sword, and the right-angle intersection of the magazine and barrel caused feeding issues. Work on the remaining three ordered units was suspended. Furthermore, during the Great Kanto Earthquake in September of that year, these prototypes were lost to fire, forcing a temporary shelving of the research.

However, in June 1924, a new order was placed with the Tokyo Artillery Arsenal, and a new unit was completed in November. It was sent to the Cavalry School for practical testing. In December, the school determined that this model had not yet reached the stage of practical utility.

In January 1925, based on the Cavalry School’s feedback, two prototypes with adjusted barrel-to-blade angles were ordered from Gas & Electric Industry Co., Ltd. These were completed in April, after which the Tokyo Artillery Arsenal was commissioned to attach the saber components. Separately, two “Large” prototypes were produced. These were based on the Prototype Otsu automatic pistol (which later became the Type 14 pistol; the Prototype Ko automatic pistol was a large 1.1 kg pistol with a 15-round magazine). Tests in August showed that the small model was generally good, but the large model performed poorly. After further modifications, both were submitted back to the Cavalry School for practical trials.

Top: Prototype Pistol-Sword. It utilizes a modified Prototype Otsu automatic pistol with a shortened barrel. Bottom: Right side of the Prototype Pistol-Sword. The connection point between the pistol and the saber hilt is clearly visible.

In January 1926, the Technical Headquarters received a report from the Cavalry School. While noting that the small number of samples and short test period made a final judgment difficult, the report stated that the connection between the pistol and sword—the vital part of the weapon—was not sufficiently robust, making its long-term durability questionable. Essentially, the cavalry branch that had originally requested the weapon ultimately rejected its adoption.

Top Right: A prototype pistol-sword created by modifying a Nambu-style automatic pistol. While the long grip might suggest it is a “Large” model, it is actually a modification of the “Small” Nambu. Top Left: A prototype pistol-sword where the trigger guard has been extended to serve as the saber’s guard (hilt). The blade is visible. Bottom: The hilt of the saber is integrated as one with the grip of the pistol.

There were several reasons for this: technical difficulties in maximizing the performance of both the sword and the pistol remained. Meanwhile, the excellent Type 14 pistol had been adopted and was soon to be issued. The cavalry concluded it was better to carry a separate pistol and a perfect saber rather than endure the inconvenience of a hybrid “chasing two hares”. Considering high production costs and maintenance difficulties, further research was deemed unnecessary. In February 1929, the project was officially canceled.

Type 94 Pistol

The history of the Japanese Type 94 pistol began as a response to a severe crisis in officer sidearms. Before its introduction, Japanese military personnel relied on either the weak and expensive 7mm Nambu pistols or the excessively heavy and bulky Type 14 models. Due to the lack of a high-quality domestic alternative, officers purchased over 30 different types of foreign pistols, creating logistical chaos regarding ammunition supply and repairs. To resolve this issue, development of a new service weapon began based on a design by Colonel Nambu, and in January 1933, the army ordered the production of a pilot batch.

Type 94 prototype pistol.

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Type 94 prototype pistol.

Magazine of the Type 94 prototype pistol.

The new pistol was subject to strict technical requirements: it had to weigh no more than 800 grams and utilize the standard 8mm cartridge. The design aimed for maximum simplicity, reliability, and cost-effectiveness, ensuring that mass production costs did not exceed 50 yen, including the holster. High penetrating power was also required—a bullet fired from a distance of 50 meters had to penetrate a pine board more than 90 mm thick. Furthermore, the pistol was to feature a double safety mechanism and be capable of disassembly without special tools.

Top: Prototype small officer’s pistol. The barrel and slide are slightly shorter than those of the large model. Bottom: Prototype large officer’s pistol. Since this was before official adoption, the Type 94 markings are, of course, absent.

During initial testing in 1934, the prototype showed promising results in terms of power and accuracy, even surpassing Browning pistols in these metrics; however, issues arose regarding slide reliability. To eliminate jams and misfires, the design was refined: the position of the slide stop was adjusted, the rear sight height was reduced to simplify production, and the trigger shape was modified for better use with gloves. Additionally, the magazine release notch was enlarged, ebonite grips were added, and the overall weight was reduced by lightening the frame.

Type 94 pistol.

Following the successful completion of re-testing in June 1934, the pistol demonstrated compliance with all design standards, achieving an impressive penetration depth of up to 140 mm at 50 meters. On December 12, 1934, the model was officially adopted as the “Type 94.” The final version featured a muzzle velocity of 285 m/s and a 6-round magazine. The adoption of this model helped standardize officer weaponry, allowing them to purchase the pistols for personal use through military arsenals.

Specification	Type 94 Pistol
Caliber	8 mm
Overall Length	181 mm
Weight	730 g
Muzzle Velocity	284 m/s
Max Range	1300 m
Capacity	6 rounds
Bullet Weight	6.6 g

Type Mo Pistol

In February 1940, the Japanese command officially classified captured Chinese 7.63mm Mauser C96 pistols (I believe that in Japanese documentation, Spanish copies of the Mauser C96 and their select-fire versions did not have any specific designation other than Mauser C96 or Type Mo) as the Type Mo Large Pistol. The weapon was granted limited-standard status, and by 1943, Japan had established its own domestic production of ammunition for this model."

A Japanese soldier with a Type Mo pistol.

Specification	Type Mo Pistol
Caliber	7.63 mm
Overall Length	645* mm
Weight	1680 g
Muzzle Velocity	450 m/s
Max Range	1000 m
Capacity	10 rounds
Bullet Weight	10.4 g

*Note: Together with the attached shoulder stock holster.

Type 1 and Type 2 Pistols

From March 13 to March 16, 1943, functionality and accuracy tests for the “Ha-Ke” type pistol were conducted at the Irako firing range. This pistol was manufactured by Bunji Hamada of the Nippon Gun Instruments Company (Nihon Jūki Kabushiki Kaisha). In the Army, it was given the secret name “Hamada Type Pistol” and was officially designated as the “Type 2 Pistol”. Colonel Yoshikazu Dogane and Lieutenant Colonel Kenji Taniguchi were the officers in charge of the testing.

Two variants of the pistol were submitted for testing: one with a 6-round magazine and two units with 8-round magazines. The results generally showed good functional performance; no serious breakdowns occurred, though it was decided to implement minor design refinements. Its accuracy was found to be comparable to that of the Type 94 pistol.

A prototype of the Type 2 pistol with an 8-round magazine for the 8mm Nambu cartridge.

This pistol was primarily developed for officers and paratrooper units. It utilizes a blowback system with a fixed barrel. The design is simple and easy to manufacture, and its functionality and durability were deemed generally satisfactory. Minor modifications were made to the recoil spring and a few other components.

A prototype was created to verify the functionality and interchangeability of the magazines. It was recognized that the pistol possessed high military value, and on October 12, 1943, it was officially adopted as a standard-issue weapon.

Type 2 pistol.

Particular note was made of the convenience of the automatic slide stop mechanism: when the ammunition was exhausted, the slide would lock in the rear position. Upon inserting a new magazine, the weapon would immediately be ready to fire (during reloading, the slide would automatically chamber a round), which was extremely effective in combat. Patents for the technical solutions were officially published in June and July of 1943 and were finalized in September and November of the same year.

Initially, a 7.65mm caliber pistol was developed based on these technical solutions. Although that specific model was not adopted by the Army, it was referred to as the “Type 1 Pistol” and served as the technical foundation for the development of the “Type 2 Pistol”.

Type 1 pistol.

Specification	Hamada Type 1 (7.65 mm)	Hamada Type 2 (8 mm)
Caliber	7.65 mm (.32 ACP)	8 mm Nambu
Overall Length	159 mm	176 mm
Weight	680 g	795 g
Magazine Capacity	9 rounds	6 rounds (Prototypes: 6 or 8)

Inagaki Pistol

The Inagaki Shiki (Inagaki Type) is a self-loading pistol developed in the early 1940s by Iwakichi Inagaki, a former subordinate of Kijiro Nambu. After retiring from the Imperial Japanese Army, Inagaki established a manufacturing business in Suginami, Tokyo, to produce this handgun. Although it was used by both the Imperial Army and Navy to supplement the shortage of standard-issue sidearms, the Inagaki was never officially standardized as a “Type” model like the Type 94 or Type 2 pistols. Total production is estimated at approximately 500 units.

Inagaki pistol.

The standard production model is a medium-sized, straight-blowback semi-automatic pistol chambered in 7.65 mm (.32 ACP) with an eight-round magazine capacity. It features a single-action concealed hammer mechanism and a 72 mm barrel that protrudes approximately 13 mm from the front of the slide. A unique characteristic of its design is the disassembly process, which requires the trigger guard to be pivoted to the left to remove the slide and barrel. Internally, the pistol utilizes 12 rifling grooves and two parallel recoil springs positioned at the rear of the slide.

In 1942, an 8 mm prototype was developed as a potential low-cost replacement for the Type 94 pistol. This version was slightly larger and heavier, but it was ultimately rejected by the Army’s Technical Research Institute. According to historical accounts, the 8 mm Inagaki was deemed unsatisfactory due to the fragility of its construction, particularly its reliance on leaf springs. Today, the Inagaki is considered the rarest of all officially adopted Japanese military handguns, with only about three or four 7.65 mm specimens and three 8 mm prototypes known to exist.

8 mm prototype Inagaki pistol.

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Inagaki pistol.

Inagaki pistol.

Inagaki pistol.

Specification	7.65 mm Model (.32 ACP)	8 mm Prototype (8 mm Nambu)
Caliber	7.65 mm (.32 ACP)	8 mm Nambu
Magazine Capacity	8 rounds	8 rounds
Overall Length	165 mm	180 mm
Weight	650 g	900 g

Sugiura Pistol

The Sugiura pistol (Sugiura Shiki) was developed in Japanese-occupied China during the Second Sino-Japanese War. Production began in 1941 at the Sugiura Factory in Beijing, which was later renamed the North China Factory. While the design is likely Japanese, the weapon is not strictly a Japanese-made pistol, as it was manufactured in China under Japanese direction. Initially intended to supply the pro-Japanese Chinese forces of the Wang Jingwei regime, these firearms were also issued to the Japanese military to compensate for material shortages, serving as both official issue and private property of officers.

The weapon was manufactured in two distinct models: a 7.65 mm (.32 ACP) version and a 6.35 mm (.25 ACP) version. The 7.65 mm model was largely a copy of the Colt Model 1903 Pocket Hammerless, mimicking its slide shape and concealed hammer mechanism, although the grip safety found on the Colt was omitted. The 6.35 mm model was a unique scaled-down version with no direct counterpart in the Colt M1903 lineup. Both variants were straight-blowback semiautomatic pistols featuring detachable eight-round magazines and wooden grip panels with crosshatched patterning.

7.65 mm Sugiura serial number 2835 (upper) and 6.35 mm Sugiura serial number 183, right side views.

Following the end of the war, the Chinese continued production of both models, leading to a total of four primary variants. The Sugiura is considered one of the rarest Imperial Japanese handguns; the estimated production of the Japanese-marked variants is approximately 430 units for the 6.35 mm model and 2,330 units for the 7.65 mm model.

Characteristic	7.65 mm Model	6.35 mm Model
Caliber	7.65 mm	6.35 mm
Cartridge	.32 ACP	.25 ACP
Magazine Capacity	8 rounds	8 rounds
Overall Length	180 mm	140 mm
Weight	907 g	482 g

Type 4 and Type 5 Pistols

In the closing months of World War II, the Imperial Japanese Navy developed two types of unusual pistols. They were intended to arm naval base guards as substitutes for scarce rifles and submachine guns. For a long time, these were believed to be ordinary signal flare guns; however, historians have discovered documents confirming their true combat purpose: firing standard 12-gauge shotshells.

Japanese shotgun shells.

Produced at the Yokosuka Naval Arsenal, these weapons were characterized by extremely poor craftsmanship. The frames featured a primitive black lacquer finish, and the construction was so unreliable that modern researchers are strongly discouraged from attempting to fire them.

Type 4 pistol.

Model Features:

• Double-Barrel Variant (Type 4): This model featured plastic grip panels and internal strikers. The mechanism cocked automatically when the barrels were “broken open” for reloading. It was equipped with a safety and a selector switch to determine the firing order of the barrels.
• Single-Barrel Variant (Type 5): An even more simplified model, constructed almost entirely from stamped sheet metal parts. Unlike the double-barrel version, it utilized an external hammer that had to be manually cocked by thumb before each shot.

Type 5 pistol.

Feature	Type 4 (Double-Barrel)	Type 5 (Single-Barrel)
Caliber	18.8 mm (12-gauge)	18.8 mm (12-gauge)
Weight	1.25 kg	0.817 kg
Overall Length	264 mm	267 mm
Barrel Length	165 mm	210 mm
Capacity	2 rounds	1 round
Cocking Method	Automatic (via unbreeching action)	Manual (external hammer)

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Type 4 pistol.

Type 4 pistol.

Type 4 pistol.

Type 4 pistol.

Type 5 pistol.

Type 5 pistol.

Type 5 pistol.

National Pistole

Designed for the defense of the nation and to equip volunteer forces, the National Pistole was a type of weapon that could be manufactured at any small factory or blacksmith shop. The design was simple, featuring a barrel formed from a common piece of pipe with a 13 mm diameter. It used a load of 3 to 5 grams of black powder, while the projectile was created by cutting an ordinary metal rod into sections approximately 15 mm long. The mechanism utilized an S-shaped spring-loaded percussion lock to strike a primer placed in a recess at the top of the breech.

National pistole and Type 14 pistole.

[_DELAVR]

SUBMACHINE GUNS

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SUBMACHINE GUNS

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Automatic Carbine 1926

The development of the experimental automatic carbine began in accordance with the Army Technical Bureau’s Research Plan approved in July 1920. Under the infantry weapons section, “automatic weapons” were categorized into automatic carbines (submachine guns) and automatic rifles.

​According to 1924 records, the project faced significant delays:

• ​Low Priority: The project was ranked last, behind light machine guns, aircraft guns, and infantry cannons.
• ​Slow Progress: By 1924, the carbine was only 10% through the design phase, while work on the automatic rifle had not yet begun.

The carbine was designed as a research foundation for future automatic rifles and was intended to be a highly portable weapon for:

• ​Support: Acting as a backup fire resource for commanders and supporting light machine guns during assaults.
• ​Specialized Crews: Equipping vehicle, boat, and train crews, as well as paratroopers and scouts.
• ​Security: Guarding railways and overseas diplomatic missions.

The Army Ministry report dated January 9, 1926 – January 21, 1926, mentions a ‘submachine gun’ chambered in 6.5 mm, with an effective range of 600 meters, a 20-round magazine, and a rate of fire of 360–420 rounds per minute. It appears that this weapon is the first Japanese submachine gun designed for an experimental cartridge using a 6.5×50mmSR Arisaka bullet, and it more closely resembled an assault rifle.

Tokyo Arsenal Model 1927 and Model 1928

The first model of the experimental submachine gun, presented in 1927, structurally inherited components from existing Japanese systems: the short-recoil automation from the Type 14 pistol and the metallic strip-feed system from the Type 3 machine gun. Initially, the primary emphasis was placed on high firepower, provided by a 50-round drum magazine.

The 1927 Tokyo Arsenal experimental submachine gun with an 18-round magazine and a 50-round drum.

However, testing revealed that the massive rate of fire of 1,200 rounds per minute led to overheating and mechanical failures. In an attempt to find a solution, various box magazines with capacities of 20–25 rounds were tested. This process ultimately led to the development of a more compact and reliable 18-round magazine.

The 1927 Tokyo Arsenal experimental submachine gun with an 18-round magazine and a 50-round drum.

The second model, created in 1928 by engineer T. Toshio, was the result of a radical design overhaul, shifting to a blowback system with a fixed barrel. An angled 18-round box magazine using standard 8mm Nambu cartridges became the standard. The primary innovation was a unique trigger mechanism featuring a ratchet system designed for either semi-automatic fire or fixed two-round bursts. Nevertheless, the selector’s design likely allowed for fully automatic fire as a technical possibility: if the ratchet gear was positioned in an intermediate setting, the disconnector would be bypassed, and the weapon would continue to fire as long as the trigger remained depressed.

Patent drawing of the 1928 Tokyo Arsenal experimental submachine gun.

Specification	First Model (1927)	Second Model (1928)
Action Type	Short recoil	Blowback
Barrel	Reciprocating (Moving)	Fixed
Overall Length	690 mm	803 mm
Barrel Length	250 mm	265 mm
Weight (Empty)	2.2 kg	3.3 kg
Primary Magazine	50-round drum/18-round box	18-round box
Fire Modes	Semi-auto / Full-auto	Semi-auto / 2-round burst / Full-auto*
Rate of Fire	~1200 rpm	300 – 600 rpm

*Note: The second model is only presumably capable of fully automatic fire.

Presumably the 1928 Tokyo Arsenal experimental submachine gun in the Yokosuka Arsenal.

The overall length to barrel length proportions shown in the photograph match the specifications of the 1928 second model provided by Jiro Sayama.

Type Be and Type Su

​The Japanese Imperial Navy’s procurement of Swiss automatic weapons began in 1929. The primary driver was an acute shortage of automatic firepower within the Special Naval Landing Forces (Rikusentai). Since the Imperial Army claimed almost the entire production of Type 11 light machine guns for itself, the Navy was forced to seek alternatives abroad. Their choice fell on the products of the SIG firm in Neuhausen, specifically the SIG 1920 (the Swiss version of the modernized MP18-I).

Type Be submachine gun.

​The first batch of 100 units was ordered in March 1929 for field testing. In the Japanese Navy’s classification system, this weapon—along with subsequent variants like the MP28—received the official designation Type Be (derived from the first syllable of the designer’s name, Bergmann; Be-shiki). While initial orders were chambered in 7.65mm Luger, the Navy switched to 7.63mm Mauser by 1931. In total, approximately 5,800 to 5,900 units of this type were purchased before 1939.

​A defining feature of the Type Be in Japanese service was its local modification. The Navy purchased ready-made submachine guns that had been in SIG’s inventory since 1927 and, at their own naval arsenals, fitted them with bayonet lugs for the standard Type 30 bayonet. This transformed them into specialized landing party weapons. The Type Be saw continuous action throughout the war, from the 1932 Shanghai Incident to the final battles across the Pacific.

​In 1935, the Japanese Navy acquired another Swiss model: the Solothurn S1-100. In the Japanese system, this model was designated Type Su (after the first syllable of the manufacturer, Solothurn; Su-shiki). Only a small batch of 100 to 150 units in 7.63mm Mauser was purchased. Due to its exceptional manufacturing complexity and very high cost, this weapon was never adopted on a mass scale.

Type Su submachine gun.

​Despite their small numbers, the Type Su units were actively used by the Rikusentai from the Kure Naval Base during operations in China. These models were also equipped with bayonets, though they typically used the Austrian M1895 pattern. Consequently, by the start of World War II, the Japanese naval marines possessed a unique arsenal of European submachine guns—the widespread Type Be and the elite Type Su —while the Imperial Army continued to operate largely without this class of weaponry.

Feature	Type Be (SIG 1920 / Bergmann)	Type Su (Solothurn S1-100)
Caliber	7.63x25mm Mauser (also 7.65x22mm)	7.63x25mm Mauser
Magazine Capacity	50 rounds (Box)	32 rounds (Box)
Overall Length	840 mm (815 mm for 7.65mm)	850 mm
Barrel Length	200 mm	200 mm
Rate of Fire	600 rpm	~750 rpm*
Weight (Empty)	~4100 g (4200 g for 7.65mm)	4250 g
Weight (Loaded)	~5100 g	4900 g

​*Note: Japanese documents state a rate of fire of 750 rounds per minute for the S1-100 submachine gun.

Model 1

This model was developed by order of the Imperial Army Technical Headquarters in the first half of the 1930s, specifically for armored vehicle crews. The primary objective was to create an ultra-compact weapon chambered for the standard 8mm Nambu cartridge that could be used effectively within the cramped confines of a tank or armored car, including firing through narrow vision slits. To achieve these minimal dimensions, the designers employed a bold layout for that era.

Model 1.

One of the most remarkable features of the Model 1 was the fire control grip, which simultaneously served as the magazine well. A massive, curved 50-round sector magazine was inserted directly into it. Due to the bottleneck shape of the 8mm Nambu cartridges, the magazine had a pronounced curve, and its baseplate featured a special folding lug to increase stability when firing from parapets or vehicle mounts.

Model 1 late.

The internal mechanism was based on a blowback system, firing from an open bolt to facilitate better cooling. The recoil spring was positioned around the barrel to save space. However, the primary technical complexity was the pneumatic buffer located at the rear of the receiver. This device allowed the rate of fire to be adjusted between 400 and 600 rounds per minute by using air resistance to slow the bolt’s travel.

Specification	Model 1
Weight (w/o magazine)	3.430 kg
Caliber	8 mm
Overall Length	620 mm
Muzzle Velocity	335 m/s
Maximum Rate of Fire	629 rpm
Minimum Rate of Fire	400 rpm
Magazine	50-round box (sector)

Model 2

Here is the translation of your text into English, based on the historical documents provided:

As one of the components of the small-caliber weapons system, a need arose to equip the army with submachine guns. The Army Technical Headquarters began preliminary research in August 1935, and in April 1936, testing began on two types of submachine guns.

Main requirements for Model 2 Ko:

• Use of special 6.5 mm caliber cartridges.
• Sufficient lethality.
• Weight (without magazine) — up to 3 kg.
• Magazine capacity — at least 30 rounds.
• Effective firing range (penetration capability) — up to 700 meters.
• Effectiveness against soldiers in winter uniforms.

Main requirements for Model 2 Otsu:

• 8.0 mm caliber, using Type 14 cartridges (8×22 mm Nambu).
• Weight — up to 2 kg.
• Magazine capacity — 50 rounds.
• Rate of fire — from 500 to 600 rounds per minute.
• Presence of a fire mode selector (semi-automatic/full-automatic) and a safety device.
• Recoil during firing should be less than that of a standard rifle.
• Absence of protruding parts on the right side of the weapon (for ease of carrying).
• Effective firing range — up to 500 meters.
• Effectiveness against soldiers in winter uniforms.

Model 2 Otsu prototype.

In June 1937, the Nambu Model 2 Ko was tested, and as the results were completely unsatisfactory regarding accuracy and functionality, further testing was discontinued. At least four Nambu Model 2 Ko submachine guns were produced.

Model 2 Ko.

It was the Model 2 Otsu that was recognized as the most promising, as it better met the needs of the infantry and cavalry as a “close combat weapon”.

Model 2 Otsu.

In 1942, at the Hoten Arsenal in Mukden (China), under the control of the Japanese military administration, work was carried out to establish small-scale production of 8mm Model 2 Otsu submachine guns adapted for installation on light armored vehicles. For this purpose, a special mounting device was installed on the front part of the stock for mounting on the swivels of motorcycles or armored cars. A metal plate was placed on the right side of the stock for attaching a brass catcher.

Model 2 Otsu Tank Version.

Model 2 Otsu Tank Version; it differs slightly from the version shown above.

Specification	Model 2 Otsu Tank Version
Cartridge	8×22 mm Nambu (Type 14)
Weight	2.83 kg
Overall length	0.66 m
Barrel length	0.24 m
Rate of fire	820 rpm
Feed system	30-round vertical box magazine

The document ‘Preparation of article on meeting and informal discussion gathering at Army Engineering Research Laboratory for school principles subordinate to Inspector General of Army Aviation’ lists the characteristics of a submachine gun without an index. They are very similar to the characteristics of the Model 2 Otsu.

Specification	Model 2 Otsu
Cartridge	8×22 mm Nambu (Type 14)
Overall length	0.63 m
Weight	3.00 kg
Muzzle velocity	334 m/s
Rate of fire	750 rpm
System of operation	Blowback (utilizing recoil energy)
Magazine	Curved box magazine (30 rounds)
Magazine weight	0.20 kg
Effective range	Approx. 300 m

Model 3 and Type 100

The Model 2 was succeeded by the Model 3, which was introduced by April 1939. Taking the feedback of the Cavalry School into account, engineers moved the magazine to the left side and reduced its capacity to 30 rounds. This immediately improved the weapon’s balance and ergonomics. Based on the results of comparative firing tests with German counterparts, the Model 3 was deemed promising and became the foundation for all subsequent developments.

Model 3 submachine gun: note the front sight, the barrel shroud, and the extended bayonet lug.

Model 3 submachine gun.

During the refinement of the “third model,” the Ko and Otsu modifications emerged. Various changes were tested on ten experimental units, including a screw-type firing pin, new safety systems, and improved barrel cooling surfaces. Ultimately, the Otsu variant proved to be more successful. However, a new problem arose—an excessive rate of fire, which caused the magazine to empty in just a couple of seconds and led to rapid barrel overheating. To solve this, designers had to significantly rework the recoil spring and the buffer.

Model 3 Ko submachine gun.

Model 3 Ko submachine gun.

The final stage came in March 1940, when the refined “Model 3 Type Otsu” passed state acceptance. The weapon was officially designated the Type 100.

Model 3 Otsu submachine gun.

Model 3 Otsu submachine gun.

Parameter	Model 3	Model 3 Ko	Model 3 Otsu	Type 100
Caliber	8 mm	8 mm	8 mm	8 mm
Overall Length	1100 mm	1097 mm	872 mm	0.87 m
Weight	3435 g	3885 g	3652 g	4.22 kg
Rate of Fire	530 rpm	755 rpm	755 rpm	700 rpm

Three variants of the submachine gun were produced during the war: an early version equipped with bipods and a bayonet lug, a folding stock version for paratroopers, and the 1944 version adapted for wartime production conditions. The latter was slightly longer and featured simplified sights, a crudely manufactured stock, and poor-quality welding, while the rate of fire was increased to 800–1000 rounds per minute.

Top: paratrooper Type 100. Bottom: late Type 100.

Early variant of the Type 100 with bipods.

Beretta M38/43

The Japanese procurement of Italian Beretta M38/43 submachine guns marked the final instance of the Imperial Japanese Navy purchasing foreign small arms. These weapons were a technologically simplified version of the original Model 1938A, adapted for mass production by shortening the barrel, removing the cooling shroud, and utilizing stamped metal parts.

The most distinctive feature of the Japanese contract was the total absence of standard factory markings. The weapons bore no manufacturer names or naval insignias. The only identifiers were Japanese inspection marks in the form of kanji characters and small letter codes on components manufactured by Beretta. Additionally, the Japanese version featured a two-piece composite beechwood stock, whereas the Italian originals used a single-piece design.

The Japanese Beretta M38/43.

Notably, Japan purchased these submachine guns exclusively with 20-round magazines, ignoring higher-capacity options. The use of the 9x19mm Parabellum cartridge—which was not standard for the Japanese military—makes the purpose of this acquisition ambiguous. The weapons were likely intended either for technical evaluation of simplified manufacturing methods or for equipping sabotage units operating behind British and Australian lines, where 9mm ammunition was readily available.

[_DELAVR]

HEAVY MACHINE GUNS

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HEAVY MACHINE GUNS

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Type Ho Siki and Type 38 Machine Guns

The Hotchkiss machine gun was the first model to feature gas-operated automation and wedge locking. Despite its general reliability, the 1898 trials in Japan revealed issues with ruptured cartridges, which were attributed to ammunition spoilage during transport across the ocean. The Hotchkiss company promised to rectify these defects, maintaining its status as the manufacturer of the best machine gun in the world.

The Hotchkiss machine gun purchased by Japan in 1897.

​Despite the incident, the Japanese Army ordered prototypes chambered in 6.5 mm. In 1901, the country acquired the manufacturing rights, and in 1902, the model was officially approved as the standard “Type Ho-Shiki” machine gun. Due to the urgent need to address the shortage of weaponry, the Japanese began mass production and, according to some reports, purchased over 200 units directly from the manufacturer.

The Type Ho-Shiki 6.5mm machine gun.

​Ultimately, the Type Ho-Shiki became Japan’s only machine gun used in the Russo-Japanese War. By the time of the Battle of the Shahe River, 100 units had been produced, equipping the 1st and 3rd Divisions. The machine gun was mounted on a tripod with a seat, and the crew consisted of four people: a commander, a gunner, a loader, and an ammunition carrier.

​In June 1907, Major Kijiro Nambu introduced the Type 38 machine gun, designed based on experience from the Russo-Japanese War as a modernization of the Type Ho-Shiki. Key improvements included the introduction of an oil reservoir for lubricating cartridges (to ease extraction), reinforced bolts and extractors, and a redesigned chamber to prevent case deformation. Additionally, a trigger lock function was added to allow for continuous fire.

Possible positions of the Type 38 on its mount.

​Despite these innovations, the machine gun retained several critical flaws. The barrel still could not be replaced in the field, and the mount remained extremely cumbersome to adjust. The design of the gas block was overly complex, and the gear-driven feed mechanism caused bullets to fall out of the rigid strips. Furthermore, a failure of the gas piston often led to severe damage or cracking of the entire gas tube.

Specification	Type 38
Caliber	6.5 mm
Length	1.448 m
Total Weight	55.5 kg
Muzzle Velocity	450 m/s
Rate of Fire	450 rpm
Feed System	Rigid Strip
Capacity	30 rounds

Type 3 Machine Gun

​By 1909, endurance tests revealed that the Type 38 suffered from extreme barrel wear and loss of accuracy after 8,000–10,000 rounds due to overheating. After experimenting with water-cooling in 1911—which proved too cumbersome—Japan shifted focus back to air-cooled designs. This led to the development of the Type 3 machine gun, officially adopted in 1914.

Key improvements in the Type 3:

• ​Controls: The pistol grip was replaced with spade grips and dual triggers.
• ​Cooling & Maintenance: Large cooling fins were added, and the barrel was made separate from the radiator to simplify replacement (though still requiring a workshop).
• ​Reliability: The complex gear-feed was replaced by a reliable horizontal reciprocating mechanism. The oil reservoir was enlarged to lubricate the entire bolt group, and dust covers were added to the receiver and ejection port.
• ​Safety & Logistics: A firing pin safety ensured the gun could only fire when fully locked. The tripod mount was simplified and fitted with wooden carrying handles.

The Type 3 machine gun.

Specification	Type 3
Caliber	6.5 mm
Length	1.204 m
Total Weight	54.1 kg
Muzzle Velocity	755 m/s
Rate of Fire	400 rpm
Feed System	Rigid Strip
Capacity	30 rounds

​In 1924, a variant of the Type 3 was tested with a hopper magazine (similar to the Type 11 LMG). While it allowed the gunner to reload using standard rifle clips without a dedicated loader, the system proved impractical for heavy machine guns and was abandoned.

The Type 3 with a hopper magazine.

By 1933, some Type 3 units were retrofitted with optical sight mounts, but major development ceased as the army transitioned to the newer Type 92.

The Type 3 with the Type 96 sight.

Heavy Machine Guns in the Imperial Japanese Navy

Due to a shortage of machine guns, the Imperial Japanese Navy ordered 20 Schwarzlose machine guns in 1911. In 1919, the Navy ordered 200 assembly kits for Maxim-Nordenfelt machine guns chambered in 7.92x57mm. Later, in 1923, Vickers machine guns were ordered (notably, the Army also received Vickers guns, as they were included with some purchased foreign tanks). These machine guns, acquired in small quantities, were issued to coastal defense units, fortresses, and mounted on ships for anti-aircraft defense.

Soldiers with the Maxim-Nordenfelt machine gun.

Type 92 Machine Gun

By the early 1930s, the 6.5mm cartridge was deemed too weak for anti-aircraft use and long-range engagement. After failed attempts to adapt aircraft machine guns for ground use, the Type 3 was deeply modernized to fire the new, powerful 7.7×58SR cartridge. This model was officially adopted in 1933 as the Type 92.

​Technical enhancements:

• ​Ergonomics: The spade grips were replaced with folding “V-shaped” handles, and the trigger was changed to a push-style lever, making it easier to fire while wearing gloves.
• ​Sighting & Recoil: The open sights were replaced with an aperture (ring) sight featuring luminescent paint for low-light conditions. A spring buffer was added to the rear of the receiver to soften the bolt’s impact during recoil.
• ​Features: A detachable flash hider was introduced, and a specialized mounting groove was added to the receiver for optical sights.

The Type 92 with the Type 96 sight and a flash hider.

Specification	Type 92
Caliber	7.7 mm
Length	1.155 m
Total Weight	55.5 kg
Muzzle Velocity	740 m/s
Rate of Fire	450 rpm
Feed System	Rigid Strip
Capacity	30 rounds

Combat experience during the Lugou Bridge Incident highlighted the vulnerability of crews, leading to the adoption of a ballistic shield in 1939. This 8 kg, 6mm-thick shield provided protection against armor-piercing rounds at distances over 200 meters.

The Type 92 with the Type 96 sight, a flash hider, and a gun shield.

​To compensate for a shortage of artillery (especially in anticipation of a conflict with the USSR), the Japanese command emphasized high-precision fire using optical sights. Three main models were developed:

• ​Type 93 (1932): A tall periscopic sight (6x magnification).
• ​Type 94 (1933): A reinforced, more durable version of the Type 93 (5x magnification).
• ​Type 96 (1935): A compact prismatic sight designed to reduce the gunner’s profile.

The Type 92 with the Type 93 sight.

Model	Type	Year	Magnification	Objective	Field of View	Weight	Height	Notes
Type 93	Periscopic	1932	6X	3.2 mm	8°	820 g	390 mm	Based on observation periscope
Type 94	Periscopic	1933	5X	3.5 mm	10°	900 g	320 mm	Reinforced, durable construction
Type 96	Prismatic	1935	4X	4.0 mm	7° – 10°*	720 – 900 g*	80 – 100 mm*	Compact design to lower profile

*Note: Range of values for Type 96 reflects differences between early and late production models.

More photos

The Type 94 sight.

The Type 92 with the Type 94 sight.

Early Type 96 sight.

Late Type 96 sight.

Mounting platform for Type 94 and Type 94 sights.

Type 98 Machine Gun

In December 1938, the Imperial Japanese Army initiated the development of the Type 98 water-cooled machine gun. The weapon was designed for installation in stationary fortifications, allowing for continuous fire. Unlike previous Hotchkiss-based systems, the Type 98 operated on a short-recoil principle, and its design was based on the Type 89 aircraft machine gun (a licensed copy of the British Vickers Class E).

​Testing of five prototypes took place between 1939 and 1940, including trials in the harsh conditions of Manchuria. The project proved to be extremely expensive, with the production of a single unit costing approximately 25,000 yen. A standout feature of the design was the forced water-cooling system utilizing a pump, which ensured barrel longevity during prolonged firing.

Early Type 98.

The Type 98 ammunition feed system standardly utilized a disintegrating metal link belt. However, some sources also claim that it was possible to use 30-round rigid strips, though it remains unclear whether this required significant modifications to the receiver design or the use of special adapters.

Late Type 98, as indicated by the “V” shaped handle.

​The ergonomics of the machine gun varied depending on the manufacturing site. Early units produced at the Hoten Arsenal used the grip and backplate from the Chinese Type 24 machine gun (a copy of the German MG.08). Later models produced at the Kokura Arsenal were fitted with the control handles from the standard Japanese Type 92 heavy machine gun.

Specification	Type 98
Caliber	7.7 mm
Length	1.09 m
Total Weight	55.5 kg
Muzzle Velocity	—
Rate of Fire	450 rpm
Feed System	Disintegrating Link Belt / Rigid Strip*
Capacity	250 rounds / 30 rounds*

Type 1 Machine Gun

In 1937, the Kokura Arsenal began developing a replacement for the Type 92. The goal was to create a machine gun that retained the power of its predecessor while being significantly lighter and more mobile for modern combat conditions. Engineers experimented with new “sled-type” mounts with three or four support points, designed to allow the weapon to be towed or moved by a crawling soldier. However, the military ultimately decided to return to a more traditional tripod design.

Experimental lightweight heavy machine gun on a sled mount.

​The modified model was officially adopted in 1942 as the Type 1. The primary changes included a transition to the rimless Type 99 (7.7×58mm) cartridge and a radical reduction in weight. By significantly reducing the size of the cooling fins and removing components such as the feed rollers and the internal oiling system, the weight of the gun body itself was reduced by approximately 10 kg. The total weight of the system, including the mount, was approximately 45 kg.

The Type 1 machine gun on a tripod mount.

Due to the smaller cooling surface, the barrel became more prone to overheating. To compensate for this, the designers simplified the barrel replacement mechanism. Although a specialized tool was still required, an experienced soldier could change the barrel in about one minute—a significant improvement over the Type 92.

The Type 1 on a Type 93 motorcycle.

​Ergonomics and controls were also updated: the rotating safety from the Type 92 was replaced by an independent lever located on the lower left side of the receiver. The tripod became lighter and more advanced, with the horizontal traverse angle increasing from 33.5° to 45°. Despite these changes, the Type 1 maintained full compatibility with the optical and anti-aircraft sights of the Type 92, and it continued to use the standard 30-round rigid strips for ammunition feed.

Specification	Type 1
Caliber	7.7 mm
Length	1.08 m
Total Weight	55.3 kg
Muzzle Velocity	730 m/s
Rate of Fire	550 rpm
Feed System	Rigid Strip
Capacity	30 rounds

[_DELAVR]

LIGHT MACHINE GUNS

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LIGHT MACHINE GUNS

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Development of the Type 11

The history of Japanese light machine guns began in 1905 with the capture of a Danish Madsen from Russian forces during the Russo-Japanese War. This trophy served as a catalyst for Captain Kijiro Nambu, who, after studying the weapon at the Army Ministry, foresaw the vital role of light automatic systems in future conflicts. His early development efforts led to the 1908 Model Ko and Otsu prototypes. These designs, heavily based on the Type 38 heavy machine gun, suffered from severe reliability issues; during trials, the Model Otsu completely broke down after only 210 rounds due to frequent misfires and pierced primers.

A Japanese light machine gun based on the Type 38 heavy machine gun. It was not possible to identify the specific model (Ko or Otsu).

​The design solutions embodied in the early Japanese light machine gun prototypes extended beyond the borders of the Empire. In March 1913, the Ordnance Department of the Republic of China initiated a standardization program, tasking the Shanghai and Dezhou arsenals with analyzing foreign automatic weapons. By June 1913, the decision was made to focus specifically on the “latest Japanese machine gun” (the 1908 prototypes based on the Type 38), modifying it to fire the standard Chinese 7.92mm Mauser cartridge. Under the leadership of Han Lin-chun at the Shanghai Arsenal, this project culminated in May 1915 with successful field trials at the Nanyuan range. The weapon was officially adopted as the Type 4 light machine gun. Today, the surviving documentation and technical data regarding the Chinese Type 4 are more comprehensive than the records for the original Japanese 1908 models, allowing researchers to effectively fill the gaps in our understanding of the Japanese prototype’s design and functionality.

The Chinese Type 4 light machine gun is a copy of the Japanese model, though it features minor differences.

Specification	Type 4
Caliber	7.92 mm
Mass	8.400 kg
Total Length	1,170 mm
Barrel Length	600 mm
Rate of Fire	450 rpm
Feed System	30-round rigid strips

More photos

Chinese Type 4 Light Machine Gun.

Chinese Type 4 Light Machine Gun.

Chinese Type 4 Light Machine Gun.

Chinese Type 4 Light Machine Gun.

Chinese Type 4 Light Machine Gun.

​Following a hiatus, development resumed in 1914 using the Type 3 heavy machine gun as a mechanical foundation. Between 1915 and 1919, the Army Technical Department experimented with various cooling and weight-reduction configurations. This period saw the creation of the 11 kg Model Ko, Otsu, and Hei variants (1915-1916), followed by specific studies into heat dissipation.

Mass (kg)	Model Ko	Model Otsu	Model Hei
Total weight	11.7	7.8	9.9
Gun weight	8.5	7.8	6.7
Tripod weight	3.2		3.2

Engineers produced a Radiator Type with a cooling jacket in 1918, and subsequently developed Non-Radiator versions to shed weight, eventually achieving a late-model variant in 1919 that weighed only 8 kg.

​

Exercises with the radiator-type machine gun.

More photos

1918 radiator-type machine gun.

1918 radiator-type machine gun.

Non-radiator type machine gun.

​A pivotal shift in the weapon’s evolution occurred in the early 1920s regarding its feeding system. In 1920, a Model Ko was developed featuring a disk magazine, reflecting a departure from the traditional rigid feed strips. However, inspired by discussions with Colonel Kunishi about the need for rapid reloading in close quarters, Nambu pivoted to a revolutionary hopper magazine. This led to the 1921 Model Otsu, which allowed the gun to be fed with standard 5-round infantry stripper clips, significantly simplifying field logistics.

Model Otsu machine gun. Note the magazine, which is identical to that of the Lewis gun. The number of ribs on the magazine and the scale are the same.

More photos

Model Otsu machine gun.

Model Otsu machine gun.

​The path to final adoption was finalized during extensive trials in 1922 at the Infantry and Cavalry Schools. While the 18 experimental samples demonstrated impressive barrel longevity—maintaining accuracy even after 20,000 rounds—the commission noted persistent issues with cartridge misalignment and ejection failures. Despite these mechanical “teething problems,” the Japanese Army leadership decided to adopt the weapon immediately as the Type 11 LMG. They prioritized the urgent need for modernization over technical perfection, planning to refine the weapon’s reliability through actual combat experience.

Type 11 serial production machine gun.

Year	Designation	Description
1908	Model Ko / Otsu	Light variant of the Type 38 machine gun.
1915-1916	Model Ko / Otsu / Hei	Light variant of the Type 3 machine gun; weight ~11 kg.
1918	Radiator Type	Features a cooling jacket for heat dissipation; weight ~10 kg.
1918	Non-Radiator (Early)	Cooling jacket removed; weight ~9 kg.
1919	Non-Radiator (Late)	Improved version of the 1918 model; weight ~8 kg.
1920	Model Ko	Equipped with a top-mounted disk magazine.
1921	Model Otsu	Predecessor to Type 11; charging handle located on the right.
1922	Type 11	Final production variant adopted by the Imperial Army.

Specification	Type 11
Caliber	6.5 mm
Overall Length	1.10 m
Total Weight	10.3 kg
Muzzle Velocity	736 m/s
Maximum Range	3700 m
Rate of Fire	500 rpm
Feed System	Hopper (using stripper clips)
Magazine Capacity	30 rounds
Bullet Weight	9 g

Type 11-based Prototypes

In March 1924, two prototypes were produced, chambered for the experimental 7.7mm cartridge. The modernization involved replacing the barrel and redesigning the chamber, hopper, and feed line to accommodate the larger ammunition. The safety mechanism and barrel attachment were also modified, and the bipod was made extendable to nearly double its length for better stability.

​Trials at the Futtsu range revealed critical structural weaknesses. While semi-automatic accuracy matched that of a 7.7mm infantry rifle, the increased power of the cartridge caused the frame to fail. Prototype No. 261 suffered a bolt group failure after 1,095 rounds, while No. 330 experienced a broken receiver pin after 3,706 rounds. The tests proved that a simple conversion of the Type 11 to a larger caliber was impossible, necessitating an entirely new design.

Presumably a 7.7mm caliber Type 11 machine gun.

By 1928, engineers addressed the Type 11’s primary weakness—the vulnerable hopper system—by developing a version with a 35-round box magazine. This radically improved reliability and reduced sensitivity to dirt.
​The weapon also received several ergonomic upgrades:

• ​Bipods capable of anti-aircraft fire.
• ​A rear monopod on the stock (similar to the later Type 99 system) to create a “tripod” effect for stability.
• ​A Lyman-style aperture sight for better accuracy.
• ​A dedicated semi-automatic fire mode.
• Although not adopted, its advancements in ergonomics and sighting were incorporated into later Japanese designs.

The only photo of a Type 11 with a box magazine. I should note that the magazine shown below matches the dimensions of a 20-round magazine more closely, but it is certainly not for 35 rounds. Furthermore, the lack of a curve on the magazine is perplexing, and the purpose of the device to the right of the magazine in the photo remains unclear. I also want to draw attention to the long horizontal magazine well; I can only speculate that 35 rounds were accommodated by both the magazine itself and the magazine well, similar to the Johnson 1941 machine gun, but unfortunately, nothing can be said for certain. Additionally, note the shortened stock, which was apparently made to simplify production or for the convenience of the cavalry.

One of the most unusual experiments was a device designed for firing from cover, overseen by Lieutenant Colonel Yoshikazu Dokin. To meet the demands of positional warfare, the design featured a folding stock with a ratchet mechanism that could be rotated 180 degrees. This allowed the soldier to fire from behind cover while aiming through a periscopic optical sight developed by Tokyo Optical. Despite reaching a functional stage, the project was canceled by 1941 due to the high cost and complexity of the optical components.

Type 11 machine gun for firing from behind cover.

As discussed in the “Bolt-action Rifle” chapter (see section “Type 38 Rifle”), inventor Kinzaburo Hibino proposed an evolution of H.P. Maxim’s silencer design. The distinctive feature of this invention was its compatibility with automatic weapons.

The 1928 device developed by Kiyoshi Kogure was a specialized suppressor designed for the Type 11 light machine gun, particularly for units mounted in armored vehicles. To prevent smoke accumulation and the stunning effect of noise on the tank crew, Kogure developed a detachable silencer featuring five concave disks. Its casing was ribbed to enhance heat dissipation and featured perforations to allow for the gradual, controlled release of propellant gases.

Kiyoshi Kogure suppressor, 1928.

On April 26, 1933, a patent was approved for a simplified suppressor model designed by Kiyoshi Kogure.

Kiyoshi Kogure suppressor, 1933.

​The 1933–1934 Tatsuo Aida attachment functioned as a universal device, combining the capabilities of a sound suppressor with a muzzle brake-compensator. Inside its cylindrical housing were eleven funnel-shaped elements. The front section of the device was equipped with specialized ribs designed to create gas turbulence, which significantly increased the efficiency of both sound and recoil suppression.

Tatsuo Aida suppressor, 1933-34.

​The 1934 Kihachi Kato suppressor was a “machine gun and rifle” device distinguished by its double-walled casing. Its most notable technical feature was the use of two internal helical (spiral) gas diffusers. The design emphasized practical field use, allowing for rapid mounting and easy cleaning, while an enlarged bore clearance ensured that the device had a minimal impact on the weapon’s ballistic accuracy.

Kihachi Kato suppressor, 1934.

​The 1935 improved Kato suppressor represented a significant modernization of his previous design, specifically adapted for the rigors of sustained automatic fire. The primary innovation was the integration of a robust radiator featuring six transverse cooling fins. The system was engineered to utilize the airflow drawn through the front slots to provide forced cooling for both the gun barrel and the suppressor body during rapid bursts.

Kihachi Kato suppressor, 1935.

Type 92 Machine Gun

Japan interest in the Lewis light machine gun began in early 1913, when Japanese representatives attended demonstrations in Bisley, England. In 1915, the Japanese firm Mitsui and Company Ltd. (Mitsui Bassan Kaisha Ltd.), with offices in major countries, contacted the Automatic Arms Company, expressing interest in acquiring manufacturing rights or purchasing Lewis guns outright. This request was forwarded to the Belgian firm Armes Automatiques Lewis, which controlled distribution rights in Asia.

Further interest in the Lewis gun only arose after World War I, during which the Imperial Japanese government was allied with Great Britain. In 1927, Mitsui and Company Ltd., representing the Japanese government, began negotiations to purchase Lewis guns directly from BSA.

By 1929, BSA was supplying commercial Lewis guns to the Japanese Navy in the standard .303 British caliber, designated 7.7x56mm by the Japanese. The gun itself was designated “留式七粍七機銃”—“7.7mm rotary machine gun.”

Lewis machine gun manufactured by BSA for the Japanese Navy.

In 1931 and 1932, the Japanese negotiated production rights with BSA, ultimately securing the necessary equipment and tooling for their own production program. In 1932 Japan officially adopted the aircraft and ground-based Lewis gun models under the designation Type 92.

Type 92 Aircraft Model with 97-Rounds disk and “shovel” stock.

The Type 92 differed in several respects from the original Lewis guns supplied by BSA. One of the main distinguishing features was the extended trigger guard. The cocking handle was located only on the left side. The gas regulator on the Type 92 had only one gas port, resulting in a stable rate of fire of 700 rounds per minute (According to American data, 600 rounds per minute.).

Specification	Type 92
Rate of Fire	700 rpm (600 rpm per US data)
Initial Velocity	740 m/s
Cartridge	7.7x56 mm
Ammo Capacity	47 and 97 Rounds
Weight (Empty)	11,79
Weight (Loaded 47)	1.87 kg
Weight (Loaded 97)	3.99 kg
Fire Mode	Automatic

Type 92 Converted For Land Use, note the rifle stock.

More photos

Type 92 Converted For Land Use, note the rifle stock.

Type 92 Converted For Land Use, note the rifle stock.

Development of the Type 96

Due to the Type 11’s overly complex hopper system and its susceptibility to jamming from dirt, the Army Technical Headquarters convened in April 1932 to design a replacement. By June, they established 15 design guidelines for a new LMG. The primary goals were reliability, simplicity, the adoption of a box magazine, a pistol grip, and a unified barrel-and-radiator assembly to allow for quick barrel changes under fire.

Four manufacturers were invited to submit prototypes: the Army Arsenal, Tokyo Gas Electric, Nippon Special Steel, and the Nambu Rifle Manufacturing Company. The design requirements were strict:

• ​Weight: Under 9 kg.
• ​Caliber: 6.5mm.
• ​Rate of Fire: Approximately 500 rounds per minute.
• ​Muzzle Velocity: At least 730 m/s.

​After initial testing at the Koishikawa Arsenal in April 1933, the designs from the Army Arsenal and Nambu were selected for further development.

Among the competing designs, the submission from Nippon Special Steel, developed by Dr. Masaya Kawamura, stood out for its highly sophisticated engineering. Unlike its rivals, Kawamura’s prototype utilized a unique locking block system where two locking lugs (flappers) were forced into recesses in the receiver by the firing pin (striker) to lock the action. A distinctive feature of its fire control group was its hybrid operation: the weapon fired from a closed bolt in semi-automatic mode for increased precision, but switched to an open bolt during fully automatic fire to prevent cook-offs. Despite its technical brilliance, the design was dropped from the competition in 1935, primarily because its staggering cyclic rate of 1,200 rounds per minute was deemed excessive for a light machine gun and led to reliability issues. However, the project was far from a failure; Kawamura’s locking mechanism proved so robust that it was later scaled up and used in the famous 20mm and 30mm (Type 5) aircraft cannons that armed legendary fighters like the Zero, Raiden, and Shiden.

Patent drawing of a machine gun by Nippon Special Steel.

Second-stage prototypes were completed by November 1933. These underwent grueling evaluations, including winter trials in North Manchuria and practical testing at the Army Infantry and Cavalry Schools. While accuracy matched the Type 11, magazine feed issues remained a point of focus.

In May 1934, the Technical Headquarters ordered third-stage prototypes to finalize the design. Two distinct models were produced:

• ​Model Ko: A hybrid design built by Nambu that combined the best features of previous prototypes.
• ​Model Otsu: An Arsenal-built design featuring a downward shell ejection system.

Model Ko machine gun from the Nambu factory. Note the absence of a bayonet lug.

Model Otsu machine gun from the Arsenal. It is a copy of the Czech ZB-26.

Specification	Model Ko	Model Otsu
Total Length	1,150 mm	1,150 mm
Barrel Length	550 mm	550 mm
Total Weight	7.980 kg	9.000 kg
Magazine Weight (Empty)	0.510 kg	0.450 kg
Magazine Weight (Full)	1.140 kg	1.080 kg
Ammunition Capacity	30 rounds	30 rounds
Muzzle Velocity	746.4 m/s	743.0 m/s
Cyclic Rate of Fire	500–600 rpm	530–650 rpm
Ejection Direction	Bottom-Right	Downward

More photos

An exhibition organized during the Emperor’s visit to the Army Technical Headquarters in 1935. Note the Model Ko machine gun.

Barrels of the Model Ko and Model Otsu machine guns.

Barrels of the Model Ko machine gun.

Following extensive accuracy tests at the Futtsu range and final winter trials, Model Ko was officially selected for adoption in August 1935. After final modifications were completed in late 1935, the weapon underwent its last practical tests in January 1936 and was officially designated as the “Experimental Type 96 Light Machine Gun.”

Type 96 machine gun with a shield and an optical sight.

Specification	Type 96
Caliber	6.5 mm
Overall Length	1.048 m
Total Weight	8.7 kg
Muzzle Velocity	735 m/s
Maximum Range	3500 m
Rate of Fire	550 rpm
Feed System	Box magazine
Magazine Capacity	30 rounds
Bullet Weight	9 g

To enhance accuracy against ground targets (up to 500 m) and aerial threats, the Type 96 machine gun was equipped with a detachable 2.5×20 mm optical sight. Due to the top-mounted magazine, the sight was offset to the right, allowing it to be used simultaneously with the iron sights. The optic lacked external adjustment knobs; all corrections for range (up to 1,600 m), windage, and aircraft speed were made using a complex internal reticle. Only 10,000 units were produced, so not all gun crews were equipped with these sights.

Reticle of the Type 96 optical sight.

ZB-26 in Japan

Czech data show that 32,272 ZB-26 machine guns were delivered to China between 1927 and 1939. Of these, 17,163 were purchased by the national government from 1937 to 1939, with the final batch of 100 units shipped in April 1939. Successful local imitation began at the Dagu Shipyard in 1927, after which various arsenals followed suit. In 1934, the Ordnance Industry Directorate adopted the Czech-style design as the standard light machine gun, and by the end of the Second Sino-Japanese War, it had become the most significant light machine gun in the country’s history.

Chinese soldiers practice shooting with the ZB-26

In 1938, the Zhejiang Iron and Steel Works also began producing an improved Light Machine Gun in the Czech style, called the Type 77, with a monthly output of 60 units. The Light Machine Gun produced by the Zhejiang Iron and Steel Works features a square rear pin, a magazine moved to the right side, a round bolt, a rifle-like rear sight on top, and a gas adjustment device.

Type 77 Light Machine Gun.

The standard 20-round magazines of ZB-26 Light Machine Gun were often insufficient, so there are reports of 30-Round Magazines and 40-Round Magazines, presumably welded from two standard magazines. No specific information about the machine guns could be found.

Comparison of 20-round and 30-round magazine in terms of manufacturing quality, one can speak of serial production.

More photos

Chinese soldier with the ZB-26 with 30-round magazine, also note the non-standard support for the Light Machine Gun.

Chinese Soldier with ZB-26 with 30-Round Magazine.

ZB-26 with a presumably 40-round magazine, made by welding two standard magazines.

The ZB-26 gained widespread popularity among the Japanese military when they captured large numbers of them during the Second Sino-Japanese War. In Japan the Light Machine Gun was Designated Type Chi Compared to the Type 11 machine gun, the Czech ZB-26 was more reliable and had a more powerful cartridge.

Japanese Soldiers with Type Chi Light Machine Guns.

To equip airfield security units, the Imperial Japanese Army purchased 2,310 ZB-26 light machine guns from Czechoslovakia in the late 1930s. The first order for 2,000 units was sent on January 10, 1939, followed by a final order of 150 on October 17, 1939. Japan adopted the weapon semi-officially as the “Type Chi 7.9mm Light Machine Gun,” producing standard Type 98 ammunition for it in local arsenals and compiling an official manual for the Type Chi in 1939.

Cover of the Type Chi machine gun manual.

The Taiyuan Arsenal in Shanxi Province produced copies of the ZB-26 and Thompson submachine guns. In 1939, under Japanese occupation, Thompson production was discontinued while ZB-26 manufacturing was restored to its previous volume to supply Japanese and Manchurian forces. Some parts and tooling were transferred to the Hoten Arsenal (formerly Mukden) to establish serial production of unlicensed ZB-26 copies, with total output estimated at 10,000 units. Around 1940, a version chambered for the Japanese 6.5x50mmSR cartridge was developed; this variant lacked official kanji markings and featured a modified 30-round Type 96 magazine, a 603mm barrel, and a total length of 1,162mm, matching the dimensions of the original prototypes. Unfortunately, it is impossible to say anything about the project’s goals or the scale of production, as the arsenal documentation was destroyed by personnel.

ZB-26 6.5mm Caliber Light Machine Gun of Mukden Arsenal.

More photos

American Soldier with a ZB-26 6.5mm with the Type 96 Magazine on the island of New Britain, territory of New Guinea, February 13, 1944.

Magazine and loading machine for ZB 26 6.5mm from the Mukden Arsenal.

Development of the Type 99 and its Modifications

The 6.5mm Type 96 LMG suffered from low stopping power and lacked ammunition compatibility with the Type 92 heavy machine gun, complicating battlefield logistics. Drawing from combat experience in China, the Army Technical Headquarters was tasked with developing a new 7.7mm light machine gun. The primary objectives were absolute reliability, a maximum weight of 11 kg, and compatibility with both rifle and heavy machine gun ammunition.

The first prototypes were completed by June 1938, followed by a second model in November. These trials successfully addressed recoil issues through the study of new cartridges. Notably, the barrel life was significantly increased, reaching an impressive 21,000 to 24,000 rounds when using Type 97 ammunition.

The Type 99 prototype was a Type 96 rechambered for 7.7 mm caliber. The rear monopod and flash hider are absent.

In early 1939, several critical improvements were implemented:

• ​Ammunition Feed: Adoption of a curved box magazine.
• ​Reliability: The chamber was redesigned to ensure smooth operation without the need for cartridge lubrication (a major flaw in earlier designs).
• ​Durability: New extractor types were tested to eliminate ejection failures, and simplified, sturdier bipods were introduced.
• ​Barrel Exchange: A new locking mechanism was developed to ensure absolute barrel interchangeability.

By May 1939, after proving that its automatic fire accuracy surpassed previous standards, the weapon underwent practical trials at the Army Infantry and Cavalry Schools. Following minor adjustments based on their feedback, the design was finalized and officially adopted as a standard service weapon in July 1939.

Type 99 machine gun.

Specification	Type 99
Caliber	7.7 mm
Overall Length	1.185 m
Total Weight	9.9 kg
Muzzle Velocity	715 m/s
Maximum Range	3500 m
Rate of Fire	550 rpm
Feed System	Box magazine
Magazine Capacity	30 rounds
Bullet Weight	11.8 g

The optical sight for the Type 99 machine gun was updated with a new reticle specifically calibrated for the 7.7mm cartridge. In 1940, development began on a new machine gun suppressor; although the specific weapon model was not identified in the documentation, the project was scheduled for completion by 1943. Given the timeline, it is highly probable that this 1940 suppressor program was intended for the Type 99 machine gun, which had been adopted just a year prior.

Reticle of the Type 99 optical sight.

In July 1944, a prototype light machine gun designed for paratrooper units (under the secret code name “Te-Ki”) was completed. Along with a concurrently developed prototype automatic cannon for paratroopers (code-named “Te-Ji”), it underwent acceptance trials at the Irago Proving Ground. However, the weapon was never officially adopted for service.

Paratrooper Type 99 machine gun.

Specification	Paratrooper Type 99
Caliber	7.7 mm
Total Length	1.19 m
Barrel Length	0.55 m
Weight (Loaded)	11.43 kg
Muzzle Velocity	714.7 m/s
Operation	Gas operated
Rate of Fire (Cyclic)	540–550 rpm
Rate of Fire (Effective)	120 rpm
Sights	200 to 1,500 m

Type 1 and Type 3 Machine Guns

​Despite the overall effectiveness of the Type 99, the Japanese military launched a development program for a next-generation light machine gun aimed at addressing the Type 99’s remaining shortcomings. This program resulted in three distinct prototypes submitted by different manufacturers.

​Type 1 Model 1, produced by the Nambu Rifle Manufacturing Company, was an enhanced version of the Type 99 with a increased rate of fire. A key feature of this model was its modular design, allowing for rapid assembly and disassembly — a characteristic specifically intended for paratroopers. It retained the standard top-mounted box magazine used by the Type 99.

Type 1 Model 1 machine guns from the Nambu factory. The Ko version is on top, and the Otsu version is on the bottom.

​Type 1 Model 2, developed by Tokyo Gas & Electric (TGE), was initially designed for dual-ammunition compatibility with both Type 99 and Type 92 7.7mm cartridges. It utilized a rigid strip-feed system, identical to the Type 92 heavy machine gun. Two variants were produced: Model 2 Ko and Model 2 Ostu, with the latter featuring a rear monopod. Notably, the stock was attached directly to the rear of the receiver rather than the underside, which improved stability and accuracy during automatic fire.

Type 1 Model 2 machine guns from the Tokyo Gas & Electric. The Ko version is on top, and the Otsu version is on the bottom.

More photos

Type 1 Model 2 machine gun on a mount.

​Type 1 Model 3, proposed by the Nagoya Arsenal, focused on ease of mass production. This model utilized a vertical box magazine inspired by the Czechoslovakian ZB-26, as this feed system was deemed simpler and more cost-effective to manufacture than previous Japanese designs.

Type 1 Model 3 machine gun. At the top is the version for firing from behind cover; in the middle is the Technical Headquarters variant; at the bottom is the Nagoya Arsenal variant.

​The experience gained from these prototypes eventually culminated in a final, unified design, also designated as the Type 3. This final iteration adopted the rigid strip-feed system as its primary method of ammunition delivery. The stock was a slimmed-down version of the Model 1 design, and the rear monopod was relocated from the buttstock to the pistol grip. In its final form, the Type 3 functioned less like a traditional light machine gun and more like an early General-Purpose Machine Gun (GPMG).

Type 3 machine gun.

[_DELAVR]

TANK MACHINE GUNS

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TANK MACHINE GUNS

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Type 91 Machine Guns

The development of specialized tank weaponry in Japan originated with exploratory research in the late 1920s. The first prototype, created in 1928 (3rd year of the Showa era) to arm experimental armored vehicles, was a 7.7mm caliber machine gun featuring a radial disk magazine with a 16-round capacity. In June 1928, factory acceptance trials were conducted; however, at that time, the design could not be brought to the stage of mass production. As an alternative solution, the Army Technical Headquarters initiated a deep modernization of the Type 11 infantry light machine gun.

The result of this effort was the Type 91 tank machine gun, officially adopted in 1932. The primary structural departure from the base infantry model was a modified hopper magazine. In place of the standard 30-round receiver, a hopper of increased height was utilized, accommodating 45 rounds (nine standard five-round clips). To ensure reliable feeding under conditions of intense vibration and jolting, internal guide lugs were integrated into the hopper, and the geometry of the clip arrangement was modified for more secure fixation.

​

Type 91 machine gun with an optical sight on bipods. Note the 45-round magazine.

Particular attention during the design of the Type 91 was devoted to the sighting system. Specifically developed Type 90 and Type 91 optical sights, featuring 1.5x magnification and a 30° field of view, were characterized by a massive, shock-resistant housing. A notable feature of the design was the relocation of the adjustment mechanisms to the receiver brackets. Vertical adjustment was performed via a geared wheel with a spring-loaded ratcheting mechanism, while windage corrections were entered using a micrometric screw on the rear mount. This separation minimized the impact of recoil on the alignment of the optical elements.

​

Optical sight for the Type 91 machine gun.

Adapting the machine gun to the confined spaces of armored fighting compartments required a revision of ergonomics. The standard Type 11 stock was replaced with a shortened pistol grip featuring a distinct spherical thickening. To protect external components of the action within the tank’s embrasure, a two-part armored shroud was employed. Despite its narrow specialization, the machine gun retained a “dual-purpose” concept: when necessary, it could be equipped with detachable bipods and a standard stock, allowing for its use as a light machine gun outside of armored vehicles.

A soldier firing a Type 91 outside of a vehicle.

Specification	Type 91
Caliber	6.5 mm
Total Length	845 mm (Short stock) / 1023 mm (Long stock)
Muzzle Velocity	736 m/s
Maximum Range	3700 m
Rate of Fire	500 rounds/min
Feed System	Hopper magazine
Magazine Capacity	45 rounds
Optical Sight Type	Periscopic Optical Sight
Magnification	1.5x
Field of View	10°

Note: Weight may vary depending on the type of stock, the presence of bipods, the use of a bulletproof shroud, the optical sight mount, and the optical sight itself.

More photos

General left-side view of the Type 91 machine gun with an optical sight mount, but without the sight itself.

Comparison of Type 11 and Type 91 machine guns; note that the Type 91 is fitted with Type 11 bipods.

Type 97 Machine Gun

Research into the creation of a new 7.7mm tank machine gun began in July 1931 with the goal of replacing the Type 91 model. The first prototype, completed in March 1934, was a modification of the Type 3 heavy machine gun, adapted for belt-feeding. However, following practical trials at the Army Cavalry School and the 2nd Tank Regiment, the system was deemed unsatisfactory due to its excessive dimensions and mass. This necessitated the development of a fundamentally different, lightweight design.

Modified Type 3 machine gun for the use of semi-rigid belts.

In 1936, comparative trials of the third-series prototypes were conducted at the Futtsu Proving Ground: Project Otsu (a modification of the Type 89 aircraft flexible machine gun) and Project Ko (based on the experimental Model B light machine gun, which utilized the ZB-26 action). Based on the test results, Model Ko was selected as the technological basis for the future Type 97. it demonstrated superiority in reliability, ease of maintenance, and ergonomics suited for the confined conditions within armored vehicles.

Type 97 machine gun prototype with a sector magazine and a rounded stock.

In 1937, during the refinement of the fourth-series prototypes, engineers identified regular feeding malfunctions caused by the use of the standard Type 92 semi-rimmed cartridge. The critical solution was found by transitioning to a fully rimless cartridge. With this ammunition type, the Model Ko action demonstrated flawless performance, removing the final technical obstacles. After making adjustments to the bolt face and the stock, the machine gun was officially adopted on February 17, 1938, under the designation Type 97.

The Type 97 machine gun can be fired using its iron sights.

Operation and Technical Equipment
The Type 97 became the standard armament for Japanese Type 89 medium tanks and Type 94 tankettes. The machine gun was equipped with a sophisticated optical sight from Tomioka Kogaku (1.5x), which featured exceptional resistance to fogging in extreme climatic conditions. Despite its specialization for tanks, the machine gun retained the capability for dismounted use: after removing the armored shroud and attaching detachable bipods and a stock, it could be utilized as an infantry support weapon.

Cutaway view of the Type 97 machine gun.

Type 1 and Type 4 Machine Guns

In the early 1940s, the Imperial Japanese Army command initiated the development of new tank armament to overcome the limitations of the Type 97 machine gun, such as its small magazine capacity and insufficient rate of fire. The first project in this direction was the Type 1, the development of which was presumably conducted by the Nagoya Arsenal. This choice of facility appears logical, as Nagoya was the production site for the Type 89 aircraft machine guns — Japanese licensed copies of the German MG 15 and MG 17.

In September 1940, two Rheinmetall machine guns — a flexible MG 15 and a fixed MG 17 — were borrowed to conduct basic trials for the Type 1 project. The research plan aimed to create a system weighing approximately 25 kg featuring belt-fed ammunition. While some American sources from that period describe the project as a “multi-barrelled gun,” this may be a misinterpretation. It is likely that this referred to the simultaneous use of components from both the MG 15 and MG 17 in the design, or perhaps intelligence reports were correct, and the Type 1 was intended for use in a twin-gun mount.

First model of the Type 1 experimental tank machine gun. Note the similarity to the MG 15 and MG 17 machine guns.

Following the determination that the German systems were difficult to adapt for tank use, engineers at the Kokura Arsenal began developing the experimental Type 4 model in 1943. It is presumably believed that the Browning action was used as the basis for this project. The impetus for this design came from commercial Colt-Browning machine guns captured in China, which the Japanese informally referred to as the “Colt”.

Second model of the Type 4 experimental tank machine gun.

The experimental Type 4 successfully passed proving ground trials in the spring of 1944 and was considered a candidate for standardization as the primary heavy tank machine gun. A key innovation was the implementation of belt-feeding, supplemented by a massive brass catcher designed to collect both links and spent cartridges. However, due to the critical state of Japanese industry and the shortage of resources at the end of the war, the Type 4 never entered serial production, leaving the Type 97 as the only mass-produced tank machine gun until the surrender of Japan.

Specification	Type 4
Caliber	7.7 mm
Gross Weight	Approx. 25 kg (including armor and accessories)
Operation	Recoil-operated
Rate of Fire	Approx. 900 rounds per minute

Note: It is possible that the specifications provided are projected (part of the technical requirements) and the actual prototype may have possessed different characteristics.

[_DELAVR]

AIRCRAFT MACHINE GUNS

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AIRCRAFT MACHINE GUNS

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Type 89 Machine Gun

The Type 89 was a specialized aircraft turret machine gun that became the primary defensive weapon for Imperial Japanese Army aircraft during the 1930s. Its development was driven by the fact that early adaptations of ground-based machine guns (such as the Type 3) failed to provide the necessary rate of fire and reliability in the air.

The machine gun was designed based on the mechanisms of the Type 11 light machine gun (Hotchkiss system) and chambered for the 7.7×58 mm SR cartridge. The creation process went through several stages:

• In 1922, a single-barrel version with a pan magazine was tested, but it was deemed to have an insufficient rate of fire.
• Influenced by French Darne aircraft machine guns, Japanese designers arrived at the idea of a twin-mount configuration. This achieved the high density of fire required for aircraft defense.
• In 1929, the system was officially adopted. It is important to note that this machine gun has no structural commonality with the “fixed” Type 89 (Vickers system) of the same name, which was mounted stationary in the nose of aircraft.

Type 89 machine gun.

The Type 89 design consisted of two Type 11 machine guns turned on their sides and connected in parallel. Each barrel had its own mechanism and operated independently. The most unusual feature was the feed system: the gun was equipped with quadrant-shaped magazines into which standard 5-round rifle clips (stripper clips) were inserted.

During the operation of the base model, a serious problem arose: empty metal clips were ejected directly overboard after firing. On heavy bombers, these flying metal pieces would damage propellers or strike the pilot’s cockpit.

Type 89 and Type 89 (Vickers system) machine guns modified for ground use.

To eliminate this defect, the Type 89 Special variant was created in 1932. It utilized an improved magazine where 18 clips were linked into a continuous belt. After the ammunition was spent, this belt of empty clips was not ejected outside but remained inside a special box, making the weapon’s use safe for the aircraft’s own structure.

Specifications	Type 89
Caliber	7.7 mm
Barrel Length	629 mm
Ammunition	7.7×58 mmSR
Magazine Capacity	100×2 (Standard Type 89)
	90×2 (Type 89 Special)
Overall Length	1,079 mm
Weight (Empty)	25 kg
Rate of Fire	700–750 rpm
Muzzle Velocity	810.3 m/s

TE 4 Machine Gun

The TE 4 machine gun was accepted into service in 1936 by the army and was mass-produced alongside its twin-barreled variant (Type 89 twin machine gun) at the same army arsenals in Tokyo, Kokura and Nagoya.

TE 4 machine gun.

It could be mounted on light bombers Ki-30, Ki-32, Ki-36, Ki-51, reconnaissance aircraft Ki-15, Ki-46 and as a secondary portable weapon on the Ki-21 bomber, Ki-48, Ki-45 heavy fighter and several other aircraft.

Dorsal gunner of a Ki-48 with a TE 4 machine gun.

In fairness, it should be noted that despite the TE 4 relatively successful and reliable design, by the start of World War II it was clearly outdated. Its rate of fire, never exceeding 730 rounds per minute, left aircraft gunners armed with it with little hope of effectively defending their aircraft. For this reason, many machine guns were repurposed for infantry service.

TE 4 machine gun modified for ground use.

Specifications	TE 4
Cartridge	7.7x58SR Arisaka
Rate of Fire	730
Muzzle Velocity	810 m/s
Weight	9.3 kg
Weight without the Disk	7.27 kg
Ammo Capacity	69 rounds
Length	1069 mm
Barrel Length	443 mm

Type 89 and Type 97 Machine Guns

During the interwar period and the initial phase of World War II, the foundation of Japanese aircraft small-arms armament consisted of the Type 89 and Type 97 7.7 mm systems, both based on the design of the British Vickers Class E machine gun. Despite their common origin, the Army and Navy variants developed decentrally, leading to significant differences in construction and logistics.

Type 97 machine gun modified for ground use.

The Type 89 was adopted by the Imperial Japanese Army in 1929. A key feature of the system was its adaptation for the 7.7 × 58 mm SR (semi-rimmed) cartridge. The machine gun was produced in two modifications — Ko and Otsu — which featured mirrored loading mechanisms for convenient installation in the nose sections of fighters (such as the Ki-27 and Ki-43). The cyclic rate of fire reached up to 1,100 rounds per minute; however, the use of a synchronizer for firing through the propeller arc reduced this figure. By 1941, the system was considered obsolete due to its small caliber and low effectiveness against armored targets.

Type 98 machine gun modified for ground use.

The Imperial Japanese Navy adopted its version of the “Vickers” under the designation Type 97 in 1937. Unlike its Army counterpart, this weapon utilized the 7.7 × 56 mm R (.303 British) cartridge, rendering Army and Navy ammunition non-interchangeable. The Type 97 was the standard fuselage armament for the A6M “Zero” fighters. It was highly valued by pilots for its flat ballistic trajectory and the reliability of its belt-fed system. A standard ammunition capacity of 700 rounds provided a duration-of-fire advantage over the low-capacity drum magazines of early 20 mm cannons.

Type 97 machine gun modified for ground use.

During the final stage of World War II (1944–1945), a shortage of standard infantry weapons and the depletion of the operational aircraft fleet led to the mass conversion of aircraft machine guns into ground-based systems.

Type 98 machine gun modified for ground use.

Specifications	Type 89 (Army)	Type 97 (Navy)
Ammunition	7.7 × 58 mm SR	7.7 × 56 mm R
Barrel Length	724 mm	727 mm
Total Length	1,035 mm	1,033 mm
Weight	12.38 kg (Ko) / 12.70 kg (Otsu)	13.3 kg
Rate of Fire	800 / 1,100 rpm	900 rpm
Muzzle Velocity	820 m/s	745 m/s

More photos

Type 97 machine gun modified for ground use.

Type 97 machine gun modified for ground use.

Type 92 Machine Gun

As stated in the “LIGHT MACHINE GUNS” chapter under the “Type 92” section, the Type 92 machine gun was adopted in 1932. Along with the infantry version, an aircraft version was also adopted, which differed from the infantry model by the absence of a barrel radiator and the use of a spade grip.

Type 92 machine gun modified for ground use.

Like many Japanese aircraft machine guns, the Type 92 was also modified into light machine guns. The design of the machine gun itself allowed for the replacement of the spade grip with a rifle-style stock.

Specification	Type 92
Rate of Fire	700 rpm (600 rpm per US data)
Initial Velocity	740 m/s
Cartridge	7.7x56 mm
Ammo Capacity	47 and 97 Rounds
Weight (Empty)	7.5 kg*
Weight (Loaded 47)	1.87 kg
Weight (Loaded 97)	3.99 kg

*Note: Mass of the aircraft version. The Type 92 weight without the magazine and bipod was calculated by subtracting the weight of a standard infantry Lewis machine gun (12 kg, according to the manual) from its casing (approximately 4.5 kg), as the weight of the aircraft Lewis gun in all sources assumes a “shovel” stock, not a rifle stock. The rate of fire is taken from Japanese sources.

More photos

Type 92 machine guns modified for ground use.

Type 92 machine gun modified for ground use.

Type 92 machine gun modified for ground use.

Type 92 machine gun modified for ground use.

Type 92 machine gun modified for ground use.

Sighting devices for Type 92 aircraft model.

Sighting devices for Type 92 aircraft model.

Sighting devices for Type 92 aircraft model.

Type 98 and Type 1 Machine Guns

In the late 1930s the Imperial Japanese Army imported and conducted performance testing of the MG 15 swivel machine gun and the MG 17 fixed machine gun, which had been manufactured by the German company Rheinmetall since 1933 and the performance of these guns was superior to that of the Type 89 swivel machine gun.

The Army decided to license-produce them as successors. Manufacturing machinery was purchased from Germany and prior to the start of domestic production, The Type 98 machine gun were provisionally adopted on June 20, 1940 and mass production began in January 1942.

Type 98 machine guns modified for ground use.

The ammunition used was the 7.92x57mm Mauser round, which was initially imported from Germany but was later copied and adopted as a set cartridge. The ammunition types used were standard round, armor-piercing round, incendiary round, and Ma 104 (high-explosive round).

Type 98 machine gun modified for ground use.

However the ammunition was incompatible with the Type 89 fixed/swivel machine gun so a machine gun using 7.7 mm ammunition was developed. This was the Type 98 Swivel Machine Gun Model 2. While the appearance remained the same, the caliber and ammunition used were different.

Type 98 machine gun modified for ground use.

The Type 1 7.9 mm swivel machine gun was a machine gun mounted on aircraft of the Imperial Japanese Navy. Like the Army Type 98 swivel machine gun it was a licensed production of the MG 15 machine gun.

American Soldier from the 4th Marine Division with a captured Type 1 swivel machine gun on Motoyama №2 Airfield February 1945, Iwo Jima.

In March 1941 the Army transferred the blueprints to the Navy, which then attempted to domestically produce ir was officially adopted in March 1942 and mass production began in April of the same year.

Specifications	Type 98
Cartridge	7.92x57mm Mauser
Weight without Magazine	7.2 kg
Weight with Magazine	11.4 kg
Total Length	1078 mm
Barrel Length	600 mm
Effective range	600m
Muzzle velocity	750 m/s
Rate of Fire	1000-1200
Ammo Capacity	Drum magazine with 75 rounds

Browning .303 Mk II and AN/M2 Machine Guns

The situation with the AN/M2 Stinger is far from unique. Conversions of Browning aircraft machine guns were popular not only among US Marines but also among the Japanese.

The British version of the AN/M2 machine gun, the British Browning .303 Mk II, was captured in large quantities by the Japanese after the conquest of Malaya, Singapore and Burma.

British soldiers of the Royal Berkshire Regiment in Mandalay, Burma 1945 with a set of recaptured machine guns. The machine guns are British Browning .303 Mk II light machine guns modified by the Japanese.

With large quantities in their possession, the Japanese decided to modify the British Browning .303 Mk II for use by the infantry, This was because the 7.7×58mm Arisaka could be used without issue by the Japanese in British Brownings. The Japanese equipped their modified machine guns with a stock, bipod, carrying handle, pistol grid and sights.

A Japanese-modified British Browning .303 Mk II.

Specifications	British Browning .303 Mk II
Caliber	.303
Cartridge	.303 or 7.7×58mm Arisaka
Weight	9.5 Kg
Muzzle Velocity	810 m/s
Rate of Fire	1150-1250
Maximum Range	914m
Length	1130
Barrel Length	610

Type 1/Ho 103 Machine Gun

The Ho-103 (officially designated by the Imperial Japanese Army as the Type 1 Fixed Aircraft Machine Gun) was the primary heavy-caliber aviation weapon utilized by the Japanese Empire during World War II. It served as the standard armament for nearly all Army fighter aircraft and was extensively employed in flexible defensive mounts on bombers.

Type 1 machine gun modified for ground use.

Development was initiated in 1939 following the Nomonhan Incident, where the combat performance of existing 7.7 mm machine guns proved insufficient against modern aircraft. Following a competitive evaluation, the design by Chuo Kogyo was selected. The Ho-103 was technically a derivative of the American Browning AN/M2 aircraft machine gun.

Type 1 machine gun modified for ground use.

A defining characteristic of the Ho-103 was its adaptation of the American mechanism to the 12.7x81mmSR (Vickers .50) cartridge. While this cartridge possessed lower muzzle energy and a less flat trajectory compared to the American 12.7x99mm round, its smaller dimensions allowed for a higher rate of fire and a reduction in the weapon’s overall weight, making it highly suitable for aircraft integration.

Type 1 machine gun modified for ground use.

During the final stages of the conflict (1944–1945), acute shortages of infantry materiel and the grounding of the air fleet led to the systematic conversion of Ho-103 machine guns for terrestrial use.

Specifications	Type 1
Mass	23 kg
Length	1,267 mm
Barrel length	800 mm
Cartridge	12.7x81mmSR Breda
Rate of fire	983 rpm
Rate of fire (synchronized)	400 rpm
Muzzle velocity	780 m/s

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GRENADE RIFLES AND LAUNCHERS

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GRENADE RIFLES AND LAUNCHERS

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Spigot Rifle Grenade Launchers

The Japanese spigot-type rifle grenade launchers employed during World War II are classified into “early” and “late” models. The early variant, documented by Allied intelligence in 1942, was designed for the 6.5-mm Type 38 rifle. It was secured to the barrel via an L-shaped slot engaging the front sight base and further stabilized by a spring extension that locked under the rifle’s cleaning rod. The late model, discovered in 1945 and referred to in Japanese naval manuals as the hasshato (firing tube), utilized a knurled collar clamping system. A critical requirement for the installation of the late model was the attachment of a bayonet, as a notch in the launcher’s base engaged the bayonet guard to prevent rotation during discharge. The grenades were propelled using specialized launching cartridges fitted with aerodynamic wooden bullets. A notable characteristic of both launcher types is the complete absence of serial numbers, manufacturer logos, or inspection stamps.

Early spigot rifle grenade launcher.

Late spigot rifle grenade launcher.

The primary multipurpose ammunition was the Type 91 high-explosive (HE) grenade, featuring a serrated cast-iron body and a pyrotechnic delay fuze with a duration of 7–8 seconds. This projectile was highly versatile, capable of being used as a hand grenade, fired from Type 10 or Type 89, or launched from a rifle spigot when fitted with a threaded finned tailpiece. For anti-personnel purposes, the Navy also utilized the Model 2 and Model 3 Modification 1 fragmentation grenades. Specifically, the Model 2 was a modified Type 99 (Ko) hand grenade filled with picric acid and equipped with an instantaneous impact fuze utilizing a pull-pin and a copper shear wire for safety and activation.

Type 91 high-explosive (HE) grenade.

Specialized auxiliary munitions included smoke and incendiary projectiles. The hexachloroethane (HC) smoke grenade was constructed from light sheet metal and lacked an internal fuze; its chemical composition was ignited directly by the flash of the launching cartridge. Additionally, white phosphorus (WP) grenades were recovered on Luzon in 1945. These munitions combined an incendiary effect with rapid smoke screen generation, as the phosphorus spontaneously ignited upon contact with atmospheric oxygen following the rupture of the casing. These projectiles are believed to have been used primarily with the late-model spigot launcher.

White phosphorus (WP) grenade.

For anti-armor engagements, the Imperial Navy developed a hollow-charge (HEAT) grenade adapted for the late-model spigot systems. The projectile featured an inertial base fuze and a ballistic cap designed to prevent the deformation of the shaped-charge cone upon impact. The efficiency of the grenade allowed for the penetration of up to 40 mm of armor plate. However, the substantial mass of the projectile generated extreme recoil, necessitating the use of recoil pads for the operator. All aforementioned types of rifle grenades were propelled using specialized wooden-bulleted blank cartridges, which featured a distinct three-point primer crimp to withstand the high pressures generated during the launching sequence.

This figure is from a 1945-dated Japanese naval manual on antitank warfare. Clockwise from top: the late spigot grenade launcher and antitank hollow-charge rifle grenade mounted on a Type 99 short rifle; late spigot grenade launcher; sectional drawing of antitank hollow-charge rifle grenade.

Type 100 Rifle Grenade Launcher

The Japanese Type 100 rifle grenade launcher was developed in 1939 by order of the Army’s Main Technical Directorate to create a system capable of launching standard hand grenades using conventional infantry weapons. During competitive trials, a design utilizing the energy of a standard ball cartridge was selected. This allowed the army to dispense with specialized blank ammunition, thereby simplifying logistics. The final version, officially adopted in 1942, featured a barrel-attachment system secured by a clamp and chain, along with a range adjustment mechanism that functioned by varying the size of a gas relief port.

Depiction of the Type 100 grenade launcher’s principle of operation.

The system’s principle of operation was based on a bullet tube through which the projectile passed unobstructed, while the propellant gases were diverted into the launcher cup to provide the grenade with momentum. Firing was conducted from a position with the rifle butt resting on the ground. The maximum range was achieved with the gas port fully closed and depended on the elevation angle of the rifle. Although the device could remain attached to the barrel at all times, official manuals required its removal for accurate aimed fire with the rifle.

Left to right: carrying pouch; 1945-dated launcher; late Type 99 (Ko) grenade; steel clip of 7.7 mm steel-cased cartridges.

The primary ammunition for this system was the Type 99 (Ko) hand grenade, which differed from its predecessors by its smooth steel body and an improved percussion fuze. Unlike the Type 97 model, the Type 99 (Ko) fuze did not require manual priming; it was activated automatically by inertia at the moment of firing. The design also included a creep spring to prevent accidental discharge and a protective shield to divert propellant gases away from the soldier’s hands. The grenade body was filled with picric acid, and the internal surface was lacquered to prevent corrosion and chemical reactions.

Se-Te Grenade Launchers

The disastrous defeat of the Imperial Japanese Army at Nomonhan caused them to question the capabilities of their antitank weapons. As a result, the army immediately started to develop new antitank weapons. Experimental antitank rifle grenades and their launchers were developed under an antitank-grenade project called “Se-Te”.

​Three experimental grenade launchers were produced; they were designated Model 1, Model 2, and Model 3. Launcher Model 1 is a spigot launcher; launcher Model 2 is a cup launcher similar to the Type 100 grenade launcher in that it has a bullet tube aligned with the rifle’s bore and an offset grenade cup; launcher Model 3 is another cup launcher, but in this case the grenade cup is aligned with the rifle’s bore. Launcher Model 2 has a removable liner, allowing it to launch grenades of two different calibers.

Experimental Se-Te grenade launchers. Right to left: the launchers are labeled Model 1, Model 2, and Model 3.

Four experimental antitank grenades were produced for use with the experimental grenade launchers. Two grenades of different calibers were used with the Model 2 grenade launcher. Some of the Se-Te grenades have propellant charges and gas ports in their bases to increase their velocities. Very little is known about these grenades, but it is known that they did not incorporate hollow-charge explosives. In fact, the se-te project was dropped when German hollow-charge technology was introduced to Japan in May 1942. The introduction of German hollow-charge technology led to the development of the Type 2 grenade launcher, which is the topic of the next chapter.

Experimental Se-Te antitank grenades. Right to left: the grenades are labeled Model 1, Model 2, Model 2, and Model 3.

Type 2 Rifle Grenade Launcher

The Japanese Type 2 rifle grenade launcher was an adaptation of the German Gewehrgranatgerät system. The device featured a 30 mm rifled barrel that was attached to the muzzle of standard Arisaka rifles. The primary ammunition range included 30 mm and 40 mm HEAT (High-Explosive Anti-Tank) grenades. Structurally, these projectiles consisted of a steel body containing a filler of RDX/TNT mix and a rifled aluminum tail section. To launch the grenade, special wooden-tipped or crimped blank cartridges were used; the energy from the propellant gases discharged the projectile from the cup.

Top: Type 2 grenade launcher on Type 38 infantry rifle with 40 mm hollow-charge grenade. Bottom: Type 2 grenade launcher on Type 99 short rifle with 30 mm hollow-charge grenade.

To achieve maximum penetration, the projectile design incorporated a hollow ballistic nose cap, which ensured the required standoff distance upon detonation. The internal explosive charge was lined with a steel cone, which formed a high-velocity shaped charge jet upon impact. Contemporary estimates suggested that the 30 mm grenade could penetrate up to 40 mm of armor plate, while the 40 mm variant could penetrate up to 50 mm. This made them a formidable threat to Allied light and medium armored vehicles. The use of a blank cartridge helped minimize wear on the rifle barrel and provided a relatively manageable recoil, comparable to firing a standard ball round.

Development was underway for a 75 mm HEAT grenade for the Type 2 grenade launcher. During the development process, two versions were produced: a long and a short version.

Dual-Use 45 mm Grenade Launchers

In 1943, the 1st Section of the 1st Army Technical Research Institute supervised the Nagoya Army Arsenal in the development of a new 45 mm grenade launcher. The purpose of this emergency development program was to create a dual-use grenade launcher that could launch the Type 99 (Ko) antipersonnel hand grenade and a new rocket-propelled 45 mm hollow-charge antitank rifle grenade. Plans called for the completion of initial experimental models by May 1943, with practical testing beginning in November 1943.

Testing of the dual-use grenade launcher was observed by German military personnel in Japan and described in a July 1944 German Military Attaché report by Niemöller, Kretschmer, and Stahmer. Colonel Paul Niemöller brought lined hollow-charge technology to Japan in May of 1942.

Experimental 45 mm grenade launchers and rocket-propelled hollow-charge antitank rifle grenades. Bottom, left to right: the launchers are designated Model 1, Model 2, and Model 3. Top, left to right: the grenades are designated Ko, Otsu, and Hei. These dual-use grenade launchers could propel both antipersonnel and antitank grenades.

Three experimental grenade launchers were produced; they were designated Model 1, Model 2, and Model 3. Each has a 45 mm rifled grenade cup. The Model 1 and Model 2 grenade launchers are similar to the Type 100 grenade launcher in that they have a bullet tube that is aligned with the rifle’s bore and an offset grenade cup. To launch a grenade, a standard ball cartridge is fired. As the bullet travels through the bullet tube, expanding gas is diverted to the grenade cup, thereby propelling the grenade. The Model 1 grenade launcher is believed to have been mounted onto the rifle using a bayonet, somewhat like mounting the Type 100 grenade launcher.

The Model 2 grenade launcher has a clamp assembly like the Type 2 grenade launcher. In addition, the Model 2 grenade launcher’s body has a stabilization fork that engages the rifle’s bayonet lug when mounted. The fork prevents the launcher from rotating. A very interesting feature of the Model 2 grenade launcher is the incorporation of a bayonet lug that allows a bayonet to be mounted onto the launcher itself.

The Model 3 launcher is a redesigned Type 2 grenade launcher where the length and diameter of the grenade cup have been increased, and a stabilization fork has been added to the launcher’s body as on the Model 2. The grenade cup of the Model 3 grenade launcher is in line with the rifle’s bore, making necessary the use of a “blank” launching cartridge. In Ordnance Technical Intelligence Report Number 19, the Model 3 grenade launcher is called the “final model” and “standard” 45 mm grenade launcher.

The experimental 45 mm grenade launchers were designed to propel both antipersonnel and antitank grenades. The antipersonnel grenade used with the launchers is the Type 99 (Ko) hand grenade. This grenade has a maximum outer diameter slightly less than 45 mm. Prior to the dual-use grenade launcher program, 45 mm hollow-charge rifle grenades were not used, so they had to be developed. Three experimental rocket-propelled 45 mm hollow-charge grenades were produced and designated Ko, Otsu, and Hei. One was adopted for production, but it is not known which one.

A rocket-propelled 45 mm hollow-charge rifle grenade was described in a July 1944 German Attaché report by Niemöller, et al. Many of the details in Niemöller’s report are echoed in a U.S. postwar report entitled Ordnance Technical Intelligence Report Number 11. The information in the U.S. report was derived directly from Japanese documents. The following description is based upon the German and U.S. reports.

The rocket-propelled hollow-charge rifle grenade was used with the Type 99 short rifle only. The overall weight of the grenade is 750 gm, and its overall length is 177.5 mm. The cone has an angle of 30 degrees and a wall thickness of 1.5 mm. The booster consists of 15 gm of RDX, and the cast hollow-charge contains 130 gm of TNT and RDX. The tailpiece is pre-rifled with a twist of 22 degrees. The tailpiece houses an instantaneous fuze that is armed centrifugally. The bottom of the tailpiece has an open jet hole and four additional holes that are closed with copper discs. The four closed holes are used as a safety feature to relieve gas pressure if it becomes too great. One 24 gm disc of rocket propellant is used. The launching cartridge is loaded with 2.7 gm of №3 cylindrical powder.

Firing the launching cartridge pushes the grenade out of the cup and ignites the rocket powder about 50 cm in front of the launcher. Total combustion time is 2.5 seconds, and the grenade’s maximum speed is 120 m/s. The range is 90 m when fired at an angle of 5 degrees. The maximum range of 390 m is obtained when launching the grenade at an angle of 45 degrees. The rifle grenade is capable of completely penetrating a 55 mm steel plate, creating a hole with a diameter of 13 mm to 15 mm.

A 1944 Japanese army production schedule indicates that plans were made for the production of 60,000 45 mm dual-purpose grenade launchers and 200,000 45 mm hollow-charge rifle grenades; however, these plans were revised later, setting production to zero for both the launcher and grenade. Thus, mass production of the 45 mm grenade launcher and hollow-charge grenade was never realized.

Prototype of an External Hollow-Charge Type 97 Grenade

During the mid-war period, rod-type shaped-charge rifle grenades were developed for the Type 97 anti-tank rifle.

Type 97 with a shaped-charge grenade.

Shaped-charge grenade for the Type 97.

Prototype of an External Hollow-Charge Rifle Grenade

This ammunition is a Type “Ta” (HEAT) rifle grenade designed to be mounted on the muzzle of a Type 99 rifle. It was intended for surprise close-range attacks against enemy tanks using a modified rifle cartridge. Compared to previous high-explosive anti-tank (HEAT) rifle grenades, this model offered superior armor penetration and was easier to manufacture.

The ammunition consists of six main components: the warhead (projectile), coupling sleeve, explosive charge, fuze, tail section, and casing.

• Total Weight (Loaded): Approximately 800 grams.
• Explosive Content: 310 grams of explosive filler housed within the body, which also includes the ballistic cap and the shaped charge cone.
• Stabilization: The tail section is equipped with four fins.

Launching the grenade required a standard Type 99 cartridge (using №3 tubular powder). The bullet was removed, and the powder charge was increased to 3.2 grams. This modification could be performed directly in the field.

To deploy the grenade, the tail rod was inserted into the rifle’s muzzle. After chambering the special cartridge, the operator had to remove the safety pin from the grenade before firing. Due to the extremely heavy recoil, it was practically impossible to fire the weapon with the stock braced against the shoulder.

• Armor Penetration: Penetrates up to 75 mm of steel armor at an angle of impact between 60 and 90 degrees.
• Effective Range: 20 to 30 meters.
• Note: The shaped charge (hollow charge) cone used in this ammunition was adapted from the Type 3 HEAT shell used by the Type 92 70mm infantry gun.

Type 3 HEAT shell used by the Type 92 70mm infantry gun.

Simplified Grenade Launchers

The Simplified Launcher was a rudimentary grenade projection device made from simple wood or galvanized iron sheets. It was designed as a substitute for the Type 100 grenade launcher and was intended to be attached to a rifle for use. In the 20th year of Showa (1945), the 1st Army Technical Research Institute created the blueprints, and individual units manufactured the devices themselves for distribution.

Simple grenade launchers. Top: Model Otsu grenade launcher for use with the Type 99 (Ko) hand grenade mounted on a Type 99 short rifle. Bottom: Model Ko grenade launcher for use with Type 97 hand grenade mounted on a Type 38 infantry rifle.

There were versions compatible with both Type 99 (Ko) hand grenades and Type 97 hand grenades. When mounted on a Type 38 infantry rifle, the maximum throwing distance was approximately 100 meters; when used with a Type 99 rifle, the range was approximately 120 meters.

Simple grenade launcher used with the Type 97 hand grenade. This launcher has a wooden body and sheet metal grenade cup. This launcher does not yet have the reinforcing wire applied.

The propellant cartridges were adapted from standard service ammunition. The bullet was removed and replaced with a press-fitted wooden plug, or alternatively, cotton or wooden wadding was used.

The Model Ko simple grenade launcher used with the Type 99 (Ko) grenade is made from wood and is wire wrapped for reinforcement.

Operating instructions:

• Before firing, the safety pin must be removed from the hand grenade.
• The grenade is then inserted gently into the launcher tube with the fuze facing forward.
• When firing from a Type 38 infantry rifle, the weapon should be set to a launch angle of 30 degrees.

The Model Otsu simple grenade launcher used with the Type 99 (Ko) grenade has a wooden body and sheet metal grenade cup. It is wire wrapped for reinforcement.

Simple Grenade Rifles

Simple grenade rifles were large-bore, black-powder weapons that were “to be used to fire everything from grenades to any kind of scrap that could be rammed into the barrel”. At least two types of simple grenade rifles were designed. One version has a bamboo barrel that is wire wrapped for reinforcement; the other has a sheet metal barrel, also with wire wrapping.

Simple grenade rifles.

New Guinea Grenade Launcher

On 31 July 1943, a Japanese manual describing an improvised cup grenade launcher was recovered at Nassau Bay, New Guinea, and translated by the Allied Translator and Interpreter Section (ATIS). Another copy of this manual was recovered at Lae, New Guinea, on 1 July 1944. On 13 July 1944, yet another copy of this manual was recovered from the “east cave” on Biak Island, off the northern coast of New Guinea. Given this manual’s prevalence on and near New Guinea, the grenade launcher described in the manual has been named the New Guinea grenade launcher; however, it should be noted that this launcher may have been developed elsewhere.

The purpose of the grenade launcher was to propel a hand grenade four to five times farther than it could be thrown by hand. The translated manual states, “It is suitable for throwing from inside pill boxes and against an enemy situated on a high position.” The grenade launcher was used to launch the Type 91 and Type 97 high-explosive hand grenades.

This grenade launcher was recommended for use with an unserviceable Type 38 rifle or with a captured enemy rifle. The method of attaching this launcher to the rifle is not clear in the translated manual, the details apparently being left to the discretion of the maker. Although the manual indicates that the grenade launcher was intended to be used with a mounted bayonet, the dimensions of the grenade launcher’s cup would likely require modification of a standard Type 30 bayonet in order to affix it.

To launch a grenade with this launcher, the grenade was placed in the cup with the fuze down and with the safety pin in place. Once aimed, the launching cartridge was fired, and the pressure of the expanding gas propelled the grenade towards the target. The flash from the burning powder also ignited the fuze’s delay charge through the gas vent hole in the fuze body. Because the fuze cover sometimes covered the gas vent hole, it was sometimes necessary to remove the fuze cover before launching the grenade.

Burma Grenade Launchers

Allied forces in Burma recovered at least three different improvised cup grenade launchers, and possibly four. Two improvised cup grenade launchers are described in an Indian intelligence document dated August 1944. The U.S. Army MARS Task Force in North-Central Burma recovered another improvised cup grenade launcher in early 1945. An Indian intelligence document dated July 1945 mentions another improvised cup grenade launcher that reportedly was made in Burma, but the document has no illustration of the launcher, so it is not known if this grenade launcher is unique.

Improvised cup grenade launchers recovered by Allied forces in Burma in 1944.

In 1944, two different types of improvised cup grenade launchers were recovered by Allied forces in Burma. Both types were used with the Type 38 infantry rifle:

• The first type: is mounted by sliding it over the muzzle of the rifle and then rotating it to engage the front sight block. This grenade launcher has a cup whose caliber is 50 mm.
• The second type: is welded to a bayonet hilt so that it can be attached to a rifle in the same manner as a bayonet. This launcher has a cup whose inner diameter is 52 mm.

The MARS Task Force took a Japanese outpost at a village called Nawhkam on 17 January 1945. An improvised grenade launcher, grenade, and launching cartridges were photographed at Nawhkam, Burma, in February 1945.

U.S. Army MARS Task Force soldier with improvised grenade launcher, Type 89 shell, improvised launching cartridges, and improvised grenade. This photograph was taken at Nawhkam, Burma, in February 1945.

Technical details:

• Components: The improvised grenade launcher is composed of a grenade cup, gas adjuster knob, and clamp assembly.
• Grenade Cup: The grenade cup is made of two pieces: a tube and base. The tube is smoothbore with an inner diameter of 51.5 mm.
• Leveling Device: The leveling device is made of a brass pendulum and steel housing, which is screwed into the base. The top of the pendulum is aligned with its housing when the axis of the launcher is at forty-five degrees.
• Gas Adjuster: The base has a gas port whose effective size can be manipulated by the adjuster knob. The knurled adjuster knob has four alignment marks numbered 0, 1, 2, and 3.

Improvised grenade launcher mounted on Type 38 infantry rifle. This type of grenade launcher was recovered by the U.S. Army MARS Task Force in the village of Nawhkam, Burma, in 1945.

According to the Indian intelligence report, an improvised 50 mm high-explosive grenade was used with the launcher:

• Body: The grenade is made from cast iron and has a length of safety fuze attached. The body is mostly 37 mm in diameter with the exception of two 50 mm rims at the top and bottom.
• Loading: There is a filling plug at the top of the grenade, which is painted red to indicate that the body has been filled with a bursting charge.
• Fuze: A detonator is crimped onto the safety fuze inside the body. The safety fuze passes through the filling plug and is routed to the bottom of the grenade through two grooves in the rims.
• Application: The free end of the safety fuze is covered with a match material. The grenade is placed into the cup bottom-first so that the flash of the launching cartridge can ignite the free end of the safety fuze.

Improvised high-explosive rifle grenade used with a “Burma manufactured” grenade launcher.

Bougainville Grenade Rifles

The Base: Type 89 Grenade Discharger The Japanese Type 89 “Knee Mortar” was an effective 50 mm rifled weapon. It utilized two types of ammunition:

• Type 91 Grenade: Range up to 190 m (did not engage the rifling).
• Type 89 Shell: Range up to 650 m. It featured a copper rotating band that expanded upon firing, engaging the rifling to create a gastight seal.

Problem and Solution In 1945 on Bougainville Island, humidity caused the standard propellant charges of the Type 89 shells to fail on a large scale. Japanese Captain Nomura developed the “grenade rifle” to make use of the still-functional high-explosive warheads.

Drawing of an improvised grenade rifle made from a Type 89 heavy grenade discharger and 6.5 mm Type 38 infantry rifle. This ingenious improvisation was designed by Captain Nomura of the Japanese 6th Division research workshops. Australian forces captured seven of these improvised grenade rifles on Bougainville Island in July 1945.

Design and application:

• Assembly: The barrel of a Type 89 grenade discharger (with the baseplate removed) was welded onto the shortened barrel of a standard service rifle (Type 38 or Type 99).
• Mechanism: A hole was drilled in the bottom of the shell so the rifle barrel could fit directly into it. The shell was then propelled by firing a blank launching cartridge from the rifle.
• Performance: The firing range was 27–274 meters. The weapon was used for both indirect fire (at 45°) and direct fire at short ranges.

Drawing of improvised grenade rifle’s Type 89 discharger barrel and shell. Note that the rifle’s barrel protrudes into the Type 89 shell’s propellant charge chamber. Given this arrangement, when the launching cartridge was fired, the expanding gas forced the rotating band of the shell into the discharger’s rifling creating a gastight seal. Given the gastight seal, the shell could be propelled a significant distance.

Several of these units were captured by Australian forces in July 1945. One specimen based on the Type 99 rifle is preserved in a museum in England.

New Britain Grenade Launcher

Australian troops captured an improvised grenade launcher on New Britain Island, likely manufactured in underground workshops in Rabaul. The device consists of a bronze cup (internal diameter of 46 mm) with two rings for mounting onto a rifle barrel.

Clockwise from left: New Britain im-provised grenade launcher; improvised hollow-charge rifle grenade made from a 333 g Type 2 hollow-charge aerial cluster bomb; wooden gas check.

​The launcher utilized a modified 333g Type 2 hollow-charge aerial bomb. Key modifications to the projectile included:

• ​Tail fins cut off flush.
• ​A steel plate secured to the bottom of the tailpiece.
• ​A hexagonal washer inserted between the charge and the tailpiece.
• ​Removal of the safety wire and creep spring.

A wooden gas check was placed into the cup first, followed by the grenade. After firing, airflow acted on the arming-screw vanes, unscrewing them to arm the grenade. The projectile detonated upon impact.

Panay Grenade Launcher

On March 18, 1945, the U.S. Army 40th Infantry Division landed on Panay Island (Philippines), where they captured a Japanese document describing an improvised cup grenade launcher. The captured instructions were dated November 1, 1944, and belonged to the 170th Independent Infantry Regiment under the command of Lieutenant Colonel Ryoichi Totsuka.

Drawing from an Allied translation of Japanese instructions for making an improvised grenade launcher from a section of bamboo. The Japanese instructions were recovered by the U.S. Army in 1945 on Panay Island, Philippines.

Design and operational features:

• Material: The launcher was made from a section of bamboo reinforced with wire.
• Attachment: It was secured to the rifle using strings.
• Ammunition: It launched a cylindrical charge of picric acid to a distance of up to 100 meters.
• Launching Cartridge: This was improvised from a standard ball cartridge by removing the bullet.
• Safety: A wooden disc had to be placed into the launcher before the picric acid charge; this disc protected the main charge from the heat and force of the launching cartridge to prevent premature detonation inside the cup.
• Firing Angle: The recommended firing angle was between twenty-five and thirty-five degrees.

[_DELAVR]

MORTARS AND GRENADE DISCHARGERS

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MORTARS AND GRENADE DISCHARGERS

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Type Ko and Type Otsu Grenade Rifle

The Type Ko grenade launcher, adopted in 1914, was a modification of the existing Type 18 Murata service rifle (model of 1885). Since these launchers were converted from rifles that already had serial numbers on their bolts, the markings do not provide information regarding which arsenal manufactured them or their specific production sequence. Structurally, the Type Ko featured a heavy wooden stock with a metal base plate, a bipod, a wooden handle, and a specialized firing cord.

Left: Type Ko grenade rifle. Right: Type Otsu grenade rifle.

The Type Ko launched high-explosive, signal, illuminating, and smoke grenades. The process involved inserting a rod attached to the grenade into the rifle barrel and firing a propellant cartridge. While the high-explosive grenades utilized an impact fuze, the pyrotechnic shells (smoke and illumination) used parachutes and time-delay fuzes. The overall system was quite bulky and required careful adjustment of direction and angle before firing.

Japanese grenadier posing in snow with Type Ko grenade rifle in firing position.

The Type Otsu grenade launcher was adopted in 1918. Unlike the previous model, it was converted from Type 30 and Type 38 rifles, with the magazines and dust cover rails removed during the process. While it followed the general design of the Type Ko, the Type Otsu was significantly more massive, particularly in its handle and support base.

Type Ko grenade rifle.

The Type Otsu was used to fire a new high-explosive grenade, which increased in weight to 2 kg and was equipped with a time-delay fuze rather than an impact one. A key feature was the adjustable brass rod; by lengthening or shortening it, the operator could control the grenade’s range. To determine the correct rod length, firing angle, and fuze timing, soldiers used a brass “calculator” kept in the accessory box.

Type Otsu grenade rifle.

Specification	Type Ko	Type Otsu
Total Length	1.15 m	1.05 m
Weight	7 kg	10.8 kg
Barrel Length	476 mm	530 mm
Caliber	12 mm	11.3 mm
Maximum Range	320 m	320 m

Type 10, Type 89 and Type 100 Grenade Dischargers

The first mass-produced model was the Type 10 grenade discharger, adopted in 1921. This was a lightweight, smoothbore weapon weighing approximately 2.5 kg, with a maximum firing range of 220 meters regulated by adjusting a gas vent that allowed propellant gases to escape. A key advantage was its versatility; beyond utilizing the Type 10 and Type 91 hand grenades, it could fire a wide spectrum of specialized munitions, including Ko and Otsu type flares, “Dragon” signal shells (black, yellow, and red smoke), and “Sea Urchin” light signals in white, red, and green.

A comparison of the Type 10 on the left and the Type 89 on the right.

The next stage of development resulted in the Type 89 heavy grenade discharger, adopted in 1930 and highly regarded during the Manchurian Incident. Unlike its predecessor, it featured a rifled barrel, weighed approximately 4.7 kg, and reached a maximum range of 670 meters by adjusting the combustion chamber volume. Its primary munition was the heavy 800-gram Type 89 shell, which possessed a powerful high-explosive effect often capable of causing panic among enemy forces. Additionally, it utilized Type 95 incendiary shells, Type 1 smoke shells, target-indicator shells in “Ko” and Otsu variants, and “Ta” series anti-tank hollow-charge grenades. The Ko armor-piercing shell was capable of penetrating 50 mm of steel, while the Otsu variant could penetrate 55 mm.

A Type 89 grenade discharger with its carrying case.

Incendiary shell.

Specification	Type 10	Type 89
Length (oa)	508 mm	609 mm
Length (barrel)	241 mm	254 mm
Weight	2.50 kg	4.65 kg
Range (Type 91)	160 m	190 m
Range (shell)	n/a	650 m
Grenade Wt	533 g	533 g
Shell Wt	n/a	794 g

In 1935, research began on the experimental Type 100 heavy grenade discharger with the goal of reaching a distance of 800 meters. This weapon utilized a new 50-mm fin-stabilized Type 2 grenade and Hei type target-indicator shells. Although the Type 100 successfully passed winter trials in Northern Manchuria in 1938, it was never formally adopted because the military prioritized the mass production of the proven Type 89. By the end of the war, amidst a severe shortage of standard artillery, “Large Grenade Dischargers” appeared as simplified “surrogate” systems for the defense of the home islands. These utilized munitions from full-sized guns, such as 70-mm shells from the Type 92 battalion gun or 100-mm shells from the Type 11 mountain gun. Among their most powerful munitions was the Type 5 armor-piercing grenade, weighing 3.2 kg and capable of engaging heavy armor. Despite the widespread use of grenade dischargers, the quality of production dropped in the final stages of the war, leading to frequent tragic accidents involving barrel bursts during firing.

Type 100 grenade discharger.

Type 100 grenade.

Type 97 and Type 3 Mortars

The 81mm Type 97 Infantry Mortar served as the primary battalion-level artillery piece of the Imperial Japanese Army. Structurally, this weapon was a licensed adaptation of the French Brandt system. Key technical modifications were primarily ergonomic; specifically, the cross-leveling assembly was relocated to the right leg of the bipod. Despite critical assessments from U.S. technical services regarding the ease of leveling, the system was characterized by high operational reliability. The ammunition suite included the Type 98 and Type 100 high-explosive rounds, equipped with both point-detonating and delay fuzes.

81mm Type 97 infantry mortar.

​The 81mm Type 3 Navy Mortar was a modification of the Type 97 system, adapted for the requirements of the Imperial Japanese Navy (IJN). During the modification process, the weapon underwent several functional changes dictated by its specific operational roles:

• ​Platform Adaptation: Initially, the mortar was mounted on naval turntable mounts utilizing arc-shaped elevation mechanisms. When transitioned to land-based use (for coastal defense and naval landing forces), the design was simplified: mobile variants were equipped with rudimentary bipods lacking cross-leveling capabilities.
• ​Design Features: A distinguishing characteristic of the naval modification was the firing pin retraction mechanism. Using a specialized screw, the firing pin could be withdrawn 3mm into the base of the bore, ensuring the safe removal of misfired rounds.
• ​Ammunition Specifics: Naval projectiles featured a more complex aerodynamic profile (12 fins compared to the 6 fins of the Army model).

81mm Type 3 Navy mortar.

Specification	81mm Type 97 (Army)	81mm Type 3 (Navy)
Barrel Length	14.1 cal	15.5 cal
Weight	66 kg	76 kg
Elevation	45° — 85°	45° — 85°
Maximum Range	2,836 m	2,800 m

Type 99 Mortar

The Japanese Type 99 81mm infantry mortar was developed in accordance with tactical and technical requirements for an ultra-lightweight medium-caliber artillery piece. The primary design feature was its exceptionally short barrel. To maintain necessary ballistic performance, the windage (the clearance between the shell’s driving band and the interior barrel wall) was significantly reduced to minimize the loss of propellant gases.

Type 99 mortar.

81mm Type 99 infantry mortar.

This design choice precluded the use of conventional drop-firing, as the tight fit of the projectile prevented it from falling freely to the base of the tube. Consequently, the weapon utilized a manual striking mechanism, initiated by hitting a camshaft with a mallet to actuate a movable firing pin. The sighting equipment was simplified, featuring an elevation scale but lacking a traverse mechanism, which constrained the speed and efficiency of indirect fire operations.

81mm Type 99 infantry mortar.

The weapon achieved high mobility by breaking down into three man-portable loads, each weighing approximately 8 kg. While the ammunition was standardized with the Type 97 81mm mortar, the Type 99’s effective range was considerably shorter due to the inherent limitations of its barrel assembly.

Specification	81mm Type 99
Barrel Length	6.7 cal
Weight	23 kg
Elevation	45° — 85°
Maximum Range	2,000 m

[_DELAVR]

ANTI-TANK RIFLES, ROCKET LAUNCHERS AND RECOILLESS GUNS

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ANTI-TANK RIFLES, ROCKET LAUNCHERS AND RECOILLESS GUNS

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13mm Anti-Tank Rifle

In the mid-1930s, the Imperial Japanese Army Technical Headquarters initiated a program to develop a lightweight anti-tank solution. The project was prompted by the excessive weight of the 37mm and 20mm artillery systems then in service, which hindered their tactical mobility and effectiveness when operating alongside forward-deployed small units. The primary objective was to produce a more compact and maneuverable weapon designated as the 13mm anti-tank rifle.

Developmental work commenced in June 1935, coinciding with the research phase of the 20mm autocannon. By December of the same year, two experimental units of the 13mm anti-tank rifle were completed. The weapon featured a net weight of less than 12 kg, an overall length of 1500 mm, and a 900 mm barrel. The muzzle velocity was recorded at 700 m/s. The internal mechanism utilized a manual bolt-action system derived from the Type 38 rifle, while a spring-loaded recoil buffer integrated into the cradle was employed to mitigate recoil forces during shoulder-fired operation.

To ensure stability during prone fire, the 13mm anti-tank rifle was equipped with a bipod at the forward end of the cradle and a monopod beneath the buttstock. The design prioritized portability, allowing a single gunner to transport the weapon fully assembled. The system utilized 13mm machine gun ammunition fed from interchangeable 5-round or 10-round box magazines.

Testing demonstrated that the 13mm anti-tank rifle was capable of penetrating 20 mm of steel armor at ranges up to 200 meters, and 15 mm at ranges up to 500 meters. Despite successful initial trials in January 1936, further development was terminated the following month in favor of the 20mm autocannon program. This prototype remains the only dedicated anti-tank rifle design in Japanese military history.

Specification	13mm Experimental AT Rifle
Caliber	13 mm
Weight	< 12 kg
Overall Length	1,500 mm
Muzzle Velocity	700 m/s
Armor Penetration	20 mm / 200 m; 15 mm / 500 m
Magazine Capacity	5/10 rounds

Type 97 Automatic Cannon

The development of the 20mm automatic cannon was initiated in 1935 as a mobile anti-tank solution for infantry units. This project proceeded in parallel with the 13mm anti-tank rifle, which was ultimately rejected due to insufficient terminal ballistic performance. In July 1937, the program was officially designated as the “Type 97.” During the design phase, Japanese engineers conducted comparative evaluations using imported Swiss Solothurn S-18/100 systems to inform the weapon’s development.

Although the design was finalized by February 1938, its official adoption was initially deferred because the system’s mass was considered excessive for infantry company-level deployment. Nevertheless, production commenced that same year to equip machine gun companies within infantry battalions. The nomenclature “automatic cannon” was formally applied due to the mechanism’s ability to autonomously perform loading and case extraction cycles.

Type 97 with shield.

The Type 97 is classified as a semi-automatic weapon. Despite sharing a common ammunition base and visual profile with the Type 98 anti-aircraft gun, this anti-tank rifle featured a distinct operating principle:

• Mechanical Operation: The Type 97 functions via gas-operated reloading. The gas block and piston assembly are located beneath the barrel. The weapon operates strictly in a semi-automatic mode, requiring a deliberate trigger pull for each subsequent shot.
• Recoil Mitigation: To manage the high kinetic energy of the 20mm cartridge, a multi-stage damping system was implemented, consisting of a muzzle brake, a hydropneumatic recuperator, and a recoiling action where the receiver recoils along the cradle rails.
• Mass and Logistics: The net weight of the system was approximately 60 kg. Effective combat operation and transport necessitated a designated squad of approximately 10 personnel.
• Economic Analysis: The unit cost was 6,400 yen, rendering it an exceptionally expensive weapon system for the period (by comparison, the Type 38 infantry rifle was priced at 77 yen).

Type 97.

Ballistic Performance and Ordnance The rated armor penetration at a 90-degree angle of incidence was as follows:

• 30 mm at a range of 220 meters;
• 20 mm at a range of 700 meters.

In addition to anti-armor roles, the weapon was effectively utilized for the suppression of fortified positions (pillboxes). The primary ammunition suite included Type 97 Armor-Piercing Tracer (AP-T) and Type 98 High-Explosive Incendiary (HEI) projectiles.

Specification	Type 97 20mm Automatic Cannon
Caliber	20 mm
Weight	~60 kg (excluding shield/mag)
Overall Length	2,090 mm
Muzzle Velocity	750 m/s
Armor Penetration	20 mm / 30 mm / 220 m; 20 mm / 700 m
Magazine Capacity	7 rounds

Type 4 Rocket Launcher

The Experimental Type 4 70 mm Rocket-Propelled Anti-Tank Launcher (designated by the secret code name “Rota”) was developed by the Imperial Japanese Army during the final stages of World War II, partially based on German technical data. The system featured a smoothbore, collapsible barrel with a total length of 1,500 mm, divided into two sections for portability. Diverging from contemporary Allied and German designs, the Japanese weapon utilized spin-stabilized projectiles. This stabilization was achieved via six rocket nozzles canted at a 25-degree angle. The firing mechanism was a mechanical percussion-based system operated by a pull-cord, which negated the requirement for an electrical ignition circuit.

Type 4 70 mm rocket launcher.

Following field trials and combat effectiveness assessments, it was concluded that the 70 mm shaped charge (HEAT) possessed insufficient penetration capabilities to reliably neutralize M4 Sherman medium tanks. Consequently, development shifted toward an upscaled 90 mm variant, designated as the Experimental 9 cm Rocket Launcher.

The prototyping phase for the 90 mm version involved three distinct experimental configurations:

• A variant featuring an ultra-short barrel length of 600 mm.
• A model utilizing an “open-top” or trough-style launch tube.
• A variant equipped with an extended 1,800 mm barrel.

In 1944, a pre-production model with a 1,500 mm barrel was manufactured based on the third prototype. Due to the increased caliber, the weapon’s weight rose to 12 kg. To manage this additional mass and ensure stability during aiming, a third support leg (monopod) was integrated into the design alongside the standard bipod. The trigger and firing assembly remained standardized with the earlier 70 mm model.

Type 4 90 mm rocket launcher.

To meet the requirements of paratrooper units (Teishin Rentai), a specialized modification of the 90 mm launcher was designed with the barrel shortened to 1,200 mm to enhance mobility. The 90 mm projectile demonstrated a significant increase in lethality, providing armor penetration of approximately 120 mm of steel plate, compared to the 80 mm penetration capability of the baseline 70 mm model.

A critical nuance exists regarding the documented penetration figures for these systems. Historical records indicate that the stated values (80 mm for the 70 mm variant and 120 mm for the 90 mm variant) were derived from tests against armor plates angled between 60° and 90°. In many instances, these figures represent the nominal thickness of the test plate rather than the effective thickness (the actual path of the jet through the metal). Applying the geometric formula b(eff)= b(nom) /cos(α) is the angle of incidence from the normal, a projectile penetrating an 80 mm plate at 60° (30° from normal) possesses an inherent penetration capability of approximately 93 mm at normal incidence. Similarly, the 120 mm figure for the 90 mm variant translates to approximately 139 mm of penetration at a 90° angle. This suggests the shaped charge performance was approximately 16% higher than simplified nominal tables might indicate.

Specification	Type 4 (70 mm)	Type 4 (90 mm)
Caliber	72 mm	90 mm
Length	1500 mm	1500 mm
Weight	approx. 8 kg	12 kg
Range	50 m to 800 m	50 m to 1080 m
Muzzle Velocity	160 m/s	106 m/s
Armor Penetration	80-100 mm	120-139 mm
Projectile Weight	4 kg	8.6 kg

8cm Navy Rocket Launcher

The 8cm Navy Anti-Tank Rocket Launcher is a specialized close-range anti-tank weapon developed for the coastal and landing units of the Imperial Japanese Navy (IJN). The conceptual design is classified as an improvised adaptation of rocket technology, intended to address the deficiency of man-portable anti-tank weaponry comparable to American “bazooka” systems. Historical evidence indicates limited operational deployment, specifically within the Yoshikawa Rocket Launcher Unit (Ito Force) during defensive operations in Manila, and during the Battle of Leyte, where Japanese forces were equipped with a shipment of 21 launchers.

8cm Navy rocket launcher.

The ordnance system consists of a smoothbore launch tube 1.5 meters in length with an internal diameter of 170 mm. The projectile is a rocket weighing 5.9 kg, with a warhead and rocket motor diameter of 80 mm. Flight stabilization is achieved through spin-stabilization, facilitated by six angled nozzles located in the base of the motor. The propellant burn time is approximately 0.4 seconds, which effectively matches the duration of the projectile’s transit through the launch tube. Ignition of the charge is achieved via a percussion-based primer.

8cm Navy rocket launcher.

The projectile is equipped with a shaped-charge (HEAT) warhead containing 530 g of RDX-based explosive filler. This type of filler is characterized by high specific energy, exceeding the performance of TNT by a factor of 1.5 by weight. According to archival data the actual penetration capability against Rolled Homogeneous Armor (RHA) is 70 mm.

8cm Navy rocket launcher.

The substantial mass of the explosive filler (530 g of RDX) provides the munition with a dual-purpose capability. In terms of overpressure and lethality radius against personnel, the 8cm rocket is comparable to 70–75 mm high-explosive (HE) field artillery shells. Consequently, this weapon is regarded as an effective tool not only for engaging armored vehicles but also for neutralizing fortified firing positions and infantry concentrations, thereby broadening its tactical application on the battlefield.

8cm Navy rocket launcher.

Specification	8cm Navy Rocket Launcher
Overall Launcher Length	1500 mm
Tube Width (Diameter)	170 mm
Tube Height	139.7 mm
Bipod Length	304.8 mm
Sight Bar Length	400 mm
Rocket Diameter	80 mm
Rocket Weight	5.9 kg
Armor Penetration	70 mm
Explosive Filler Weight	530 g

8cm Navy rocket launcher.

Type 5 Recoilless Gun

The Experimental Type 5 45 mm Simplified Recoilless Gun was a prototype short-range anti-tank weapon developed by the First Army Technical Research Institute of the Imperial Japanese Army between 1943 and 1944. The project originated from an effort to identify cost-effective and simplified methods for engaging enemy armored vehicles. In late 1944, a production order for prototypes was issued to the Osaka Army Arsenal; however, the system remained in the experimental phase and was never formally adopted for mass production or active service.

Type 5 recoilless gun.

The design of the weapon was highly simplified, utilizing the principle of counter-mass dynamics to eliminate recoil. Its primary component consisted of a steel tube 1,000 mm in length with a wall thickness of 4 mm. A conical nozzle was threaded onto the breech to facilitate the exhaustion of propellant gases. The weapon was a muzzle-loading system, providing an effective acceleration length of 600 mm within the bore. It featured a rudimentary vertical grip, forward of which was mounted a firing mechanism consisting of an external hammer and a primer chamber configured to accept a modified 7.7 mm cartridge casing as an igniter.

Type 5 recoilless gun.

The armament for this system consisted of the Type 5 80 mm HEAT (High-Explosive Anti-Tank) grenade, weighing a total of 2,300 g. The projectile featured a composite construction, utilizing a metal warhead and an elongated wooden tail assembly for flight stabilization. The warhead contained 675 g of explosive filler, capable of penetrating up to 100 mm of homogeneous armor plate. A 100 g propellant charge, encased in a paper sleeve, was attached to the projectile prior to loading. A notable characteristic of the system was the complete absence of integrated sighting devices, which severely limited its accuracy.

Type 5 recoilless gun shell.

The armament consisted of the Type 5 80 mm HEAT (High-Explosive Anti-Tank) grenade, weighing 2,300 g. The projectile featured a metal warhead and an elongated wooden tail for flight stabilization. The warhead contained 675 g of explosive filler, capable of penetrating a 100 mm steel plate at impact angles ranging from 45 to 90 degrees. Geometrically, at a 45-degree angle, this indicates the cumulative jet could penetrate an effective thickness of approximately 141 mm of steel, although the reliability of the fuse decreased at angles below 40 degrees.

Type 5 recoilless gun.

Tactical employment involved firing from various positions, including shoulder-mounted or underarm stances. Due to the lack of sights and low muzzle velocity, the effective engagement range was restricted to approximately 30 meters, despite a maximum ballistic range of 150 meters. Operational utility was further constrained by a significant backblast danger zone extending up to 20 meters behind the weapon. This prevented use within enclosed spaces and required strict adherence to safety protocols to avoid injury to the operator and nearby personnel from the high-velocity gas discharge.

Specification	Type 5 Recoilless Gun
Bore Caliber	45 mm
Barrel Length	1,000 mm
Projectile Weight	2,300 g
Explosive Filler	675 g
Rocket Weight	2.3 kg
Armor Penetration	100-141 mm

[FNFAL2017]

[TheSaboteur59]

Great and Based post as always.

[TheSaboteur59]

@_DELAVR

Type Heiki Rifle

The Type Heiki was a proprietary military rifle project proposed by the private firm Nippon Heiki Seizo Co., Ltd. (Japanese Ordnance Manufacturing), based in Osaka, during the late Taisho era. On November 15, 1917, the company submitted a formal application to War Minister Kenichi Oshima for the trial production of military rifles.

The project’s primary technical consultant was Shinjiro Kobayashi, a retired Colonel of Artillery. Kobayashi brought extensive expertise from the Tokyo Artillery Arsenal and had previously conducted state-sponsored studies of firearms manufacturing in the United States, Germany, France, and Great Britain. His influence is evident in the design’s departure from standard Japanese ordnance toward Western, specifically British, engineering concepts.

Type Heiki rifle

The barrel was constructed from high-grade special steel with a 6.5 mm caliber and a total length of 760 mm. The bore featured six-groove rifling. The sighting system utilized a fixed base zeroed at 350 meters, with a maximum graduation extending to 2,500 meters. The projected muzzle velocity was 800 m/s, a figure notably higher than the standard Type 38 Arisaka (762 m/s).

The receiver featured a unique rectangular aperture located above the chamber area. This design allowed for a visual confirmation of cartridge seating and served as a gas relief port to divert pressure away from the shooter in the event of a case rupture. The bolt action was designed for high-speed operation, allowing the cycle to be completed in a single, angled motion.

A defining feature of the Type Heiki was its 10-round capacity, achieved through a vertical box magazine. This doubled the capacity of the Imperial Japanese Army’s standard Type 38 and Type 44 rifles (5 rounds). The magazine utilized a single-plate leaf spring rather than a coil spring, intended to reduce mechanical failure and optimize internal space.

A safety lever was positioned behind the trigger guard. The rifle utilized a “safe fire” system where the sear would not release unless the safety lever and the trigger were depressed simultaneously, preventing accidental discharge upon impact. To mitigate heat transfer, a “radiator wall” made of soft iron with granular protrusions was installed between the barrel and the wooden stock. This component was designed to accelerate cooling and prevent the walnut or beech-wood furniture from charring during sustained fire.

Nippon Heiki Seizo possessed a substantial industrial base, with a facility covering approximately 1.85 hectares and employing 2,500 workers. However, the project faced significant procurement hurdles. Despite receiving official permits from the War Ministry (December 1917) and the Home Ministry (March 1918), the production of the 500-unit trial batch was paralyzed by supply chain disruptions. By July 1918, the barrel-grade steel—which was strictly regulated by the Ministry of Agriculture and Commerce—had failed to arrive. Historians suggest this was due to the extreme demand for domestic steel by state arsenals during World War I, which left private manufacturers with little to no raw materials.

There is currently no definitive archival evidence to confirm that a functional prototype of the Type Heiki was ever completed. While the technical plans and industrial preparations were exhaustive, the subsequent fate of the project remains unknown, and no surviving examples have been identified in historical collections.

Japanase Lee-Enfield? We definitely need this for Japanese TT

[OggeKing]

Definitely bookmarking this page for when I have time enough to read it all!

[Emperor_Yoshiro]

[Emperor_Yoshiro]

@_DELAVR

and the purpose of the device to the right of the magazine in the photo remains unclear.

I must find a website in the past there was a website about Type 11 that is being loaded with stripper clips 5 rounds with such device since if you remove hopper there is no feeding mechanism and this thing basically is feeding mechanism. But I must search for it it was long time ago.

[Aussie-Tachanka]

Absolutely incredibly put together thread and invaluable to documenting and suggesting Japanese small arms.

I truly do and sincerely thank you DELAVR Killerwolf1024 Slakrrrrrr NonNational skultew1234 VINICIUS LAG@live for every bit of collaborative contribution in this. Along with everyone else who’s put in so much incredible work researching and suggesting items for Japan.