Hi.
Not sure about that, sorry.
regarding muzzle velocity:
The japanese ammunition for 75 mm guns (type Meiji 38 field gun, type Meiji 41 75 mm cavalry gun, type Meiji 41 pack howitzer/infantry gun, type 94 pack howitzer) has been standardized in the late 1920th. The ammunition was patronized. So muzzle velocity and range depends mainly on the barrel length and elevation.
I have no exact infos on the particular muzzle velocities.
Yours
tom!
