Towards the end of WWI, the Japanese military would experience the 7.7mm projectiles in the form of the .303 British cartridge for machine guns mounted on early aircraft like the Ro-Go Ko-gata seaplane.

[7] In 1937, however, rimless cartridges were found to have better performance in tests of Kijiro Nambu's ZB-30 clone, the Type 97 in-vehicle heavy machine gun fed with straight double-stack magazines (Zbrojovka Brno held a patent on a curved one for rimmed rounds, but for some reason Japanese hadn't copied it[8]).

[11] This effectively allowed the older 7.7×58mm variants, including the specialized ammunition, to be chambered into the Type 99 rifles and light machine guns with some discrepancy in accuracy due to the different bullet weights.

Nevertheless, the existing semi-rimmed cartridges would remain in service for the Type 92 heavy machine gun during World War II.

Factory loaded ammunition and brass cases are available from Norma, Graf's, and Hornady, Sierra and Speer also produce usable bullets.