The 7.7X58mm Japanese (7.7X58mm Japanese Arisaka) was introduced in 1939 as a replacement for the long-outdated 6.5X50mm cartridge and rifle. There were actually two versions, rimless for rifle and semi-rimmed for machine guns, which must have been a major logistics nightmare! Both used a .311-inch bullet diameter, with a 181-grain bullet for rifles in the rimless version and a 201-grain bullet in the semi-rimmed version. Velocities were a slow 2370 fps for the former; and a much more credible 2380 fps for the heavier bullet. Fielding of the 7.7X58mm was never completed before war's end, so the 7.7X58mm is less common than its 6.5X50mm predecessor. Factory ammunition remains available.
