The real problem came in getting 6.5mm ammo to the troops who were armed with Type 38 rifles, and 7.7mm ammo to the troops armed with Type 99s.
With the 6.5mm there was an additional problem of the Type 11 light machine gun. It was originally designed to use the standard 6.5mm ammunition loaded on stripper clips designed for the Type 38 rifle, but the round was too powerful and caused reliability problems.
Instead of simply redesigning the gun to allow its use with standard rifle ammo, the Japanese developed a downloaded round. Once it was removed from its packaging, it was indistinguishable from the from the ammo for the Type 38.
"The gift which I am sending you is called a dog, and is in fact the most precious and valuable possession of mankind" -Theodorus Gaza
Baby Jesus cries when the fat redneck doesn't have military-grade firepower.