In 1928, Taiyuan Arsenal made a copy version of the Thompson M1923, and named it ‘‘Type 17 assault machine gun’’. With the longer barrel and a straight stock.
During WW2, Japan captured this gun from the Chinese army, which has a 50 rounds drum magazine.

The original M1923’s rate of fire is 400 rounds per minute in order to fire the .45 Remington–Thompson (11.4x25mm).However, the Type 17 still chambered in .45 ACP, which means that the rate of fire might still as same as an ordinary Taiyuan Arsenal Thompson(800 rpm), because it already adopt the bipod and straight stock to increase accuracy, changing inner part to reduce the rpm would not be a good idea for manufacture.
Here are some pictures of the Type 17.


With the longer barrel, the damage could increase to 9-10, which would be suitable for an assault rifle, the 50 rounds magazine and 800rpm would provide good fire power for Japan BR 5.
By the way, even with lower 400rpm, it would still be a useful weapon in high BR, with straight stock and bipod, the recoil would be more manageable.
Source
晋造汤姆逊,芝加哥打字机的中国高仿版,民国产量第一的冲锋枪_腾讯新闻
中国人在汤姆森冲锋枪上搞出了多少新花样?那真是一派勃勃生机万物竞发的景象那……_腾讯新闻
History of an Icon - Auto-Ordnance | Original manufacturer of the world famous "Tommy Gun"
Do you want Japan get the Type 17 as BP weapons?
- Yes
- Nope
Which BR and rpm would be reasonable?
- BR 5 (800rpm)
- BR 5 (400rpm)
- BR 4 (400rpm)
What type of weapons should it be?
- As submachine gun.
- As assault rifle.
