According to a hunting catalog of Takahashi gun shop from 1937, Japan did imported the Belgian version of the Remington Model 8.It’s chambered with .35 Remington( 9.1 x 49 mm),which is more powerful than the 6.5 Arisaka at close range.
So far, Japan only has 2 6.5mm semiauto rifles in BR2, they do need a semiauto with better damage.
Japan’s one here can compete with the Fedorov 1912 on the tech tree, which is a pretty good idea.
I think we could also give the Soviets a low-damage semi-automatic rifle (like the American M1 Carbine), and high-damage semi-automatic rifles for the US and Germany could also be added to the game.
I recommend these three:
Soviet: SKK-44 (Kalashnikov 1944 Carbine)
Maybe the SKS 45, the first protos were sent to the 1st Belorrussian front in 1945 for battle trials during the battle of Berlin. Instead of some unknown proto, it should be a weapon that was used by the Red Army during WW2. It would have base damage of 8,2 and would use 10 round stripper clips for loading.
I remember this gun only appeared during the Cold War, right? Is there any authoritative evidence to prove its appearance in the Battle of Berlin and the Belarusian front?