There were different versions of the Ha-Go believe it or not.
The first produced versions in 1935-1936 featured 6.5mm Type 91 Light Machine guns and the 37mm Type 94 Tank gun
From 1937 the Ha-Go’s featured 7.7mm Type 97 Tank machine guns instead but still featured the 37mm Type 94 Tank Gun
At some point in 1938 the Ha-Go’s began to be armed with 37mm Type 98 Tank Gun. All Ha-Go’s from 1938 used this new higher velocity 37mm Tank gun.
The 37mm Type 94 AP and 37mm Type 1 AP were made with different cartridges for different guns.
Type 94 37mm Tank gun was chambered for the 5.3 inch cartridge which gave 37mm Type 94 AP the muzzle velocity of 575m/s
Type 98 37mm Tank Gun was identical to its predecessor in the design and even the barrel length, what essentially was different is that it was rechambered to use the 6.5 inch cartridge which was the one the 37mm Type 94 Field Gun * version was already using.
*Note that the Type 94 37mm Tank Gun and Type 94 37mm Field Gun are 2 seperate different guns.
37mm Type 94 AP with 6.5 inch cartridge had 685m/s muzzle velocity. In 1941 the Type 1 AP was introduced and with the 6.5 inch cartridge had 704m/s muzzle velocity. The Ha-Go could shoot both the Type 94 AP and Type 1 AP.
This from Japanese Tank and Anti Tank Warfare document
Furthermore the Ha-Go could also use 37mm Type 94 HE round which featured 62.3g of TNT equivalent.
When shot from Type 94 Tank Gun using the 5.3 inch cartridge, the muzzle velocity was 579m/s.
When shot from Type 98 Tank Gun using the 6.5 inch cartridge, the muzzle velocity was 707m/s
Approximate effective radius of 8 meters which is a lot for a 37mm HE especially when you realise that it is a diameter of approximately 16 meters. This round has 62-63g TNT equivalent compared to 38-39g TNT equivalent for US 37mm HE rounds
Personally I think Gaijin should model the Ha-Go tank with the Type 98 37mm Tank Gun instead since that was the new standard all the way since 1938 and the war in the Pacific only really kicked off in 1942, it should be equipped with Type 1 37mm AP which the Japanese introduced in 1941.
Type 98 37mm L/46
Type 1 AP (0.726kg)
Penetration:
55mm @ 0m at 0 ° — 704m/s
24mm @ 0m at 60 °
40mm @ 500m at 0 ° — 563m/s
18mm @ 500m at 60 °
With its historical penetration it would be able to penetrate the frontal armour of M3 Stuart’s up to 500 meters and the side armour of M4 Sherman Tanks up to like 550 meters or so. As for weaker tanks such as the M2A4 Light tank, the Ha-Go would penetrate this one up to 1000 meters from the front.
Note that the 37mm Type 94 Field Gun and the Type 98 Tank gun have identical performance since they both use the 6.5 inch cartridge,
40mm at 500m / 30mm @ 1000m
Demarre Equation: 37mm AP penetration at different velocities. Ballistic Factor is 6400
Muzzle Velocity: 704m/s
Velocity at 500m: 563m/s
Velocity at 1000m: 450m/s
Furthermore… with its 37mm HE round which has far more TNT equivalent than the US 37mm HE rounds… it would be very potent against open vehicles such as M13 MGMC and infantry in general. I’d rather see Japanese noob new players spamming fixed Type 95 Ha-Go tanks instead of those terrible Ta-Se vehicles.