my bad, wrote 40 when I meant 39.
Another interesting tidbit, for equipment dating 1940, the Japanese Army used "type 100" while the Navy used "type 0". probably to reduce the confusion, although it seems that reducing confusion was not something the Japanese miliary excelled in, evidenced by 3 (or more?) different types of 7.7mm ammo, not interchangable. And other things....
Supply officer had to have been one of the most aggrivating and frustrating positions in the Japanese military....
All else being equal (and it almost never is) bigger bullets tend to work better.