The 7.7x58 Japanese Arisaka (7.7mm Jap)
By Chuck Hawks
The 7.7x58mm cartridge was adopted by the Japanese military in 1939. To the best of my knowledge, it has never been offered in a production sporting rifle. The Japanese military load gave a 175 grain spitzer bullet a MV of 2400 fps at a pressure of about 42,000 psi.
The 7.7mm Japanese uses the same .311-.312" diameter bullets as the .303 British. The rimless, bottleneck case is 58mm (2.27") long and the shoulder angle is 25.5 degrees. This case has a .470" rim diameter.
After the surrender of the Japanese Empire in 1945, 7.7mm Arisaka rifles began appearing in the US as war trophies and military surplus. Testing revealed that the 7.7x58 will do anything that can be done with the .303 British, and more. The Arisaka Model 99 is a stronger action than the Lee-Enfield.
7.7x58 ammunition is factory loaded by Norma of Sweden. A 174 grain bullet is offered at a muzzle velocity (MV) of 2493 fps with 2402 ft. lbs. of muzzle energy (ME). Norma also offers a factory load using a 180 grain bullet at a MV of 2493 fps and ME of 2485 ft. lbs.
Norma 7.7mm factory loads use American style Boxer primers and are fully reloadable. Norma also offers virgin 7.7x58 brass to handloaders. Hornady, Sierra, and Speer offer suitable hunting bullets for the 7.7x58 of 125, 150, 174, and 180 grains. The Hodgdon, Hornady, and Sierra reloading manuals cover the 7.7x58. As with any .30-.303 cartridge, the 150 grain and 180 grain bullets are the most popular.
According to the second edition of the Sierra Bullets Reloading Manual their 150 grain spitzer bullet can be driven to a MV of 2300 fps with 39.9 grains of IMR 3031 powder, and a MV of 2700 fps with 45.6 grains of IMR 3031. The latter load develops 2428 ft. lbs. of muzzle energy. The trajectory of that load looks like this (Sierra figures): +2.09" at 100 yards, 0 at 200 yards, -8.91" at 300 yards.
The Sierra 180 grain spitzer bullet can be driven to a MV of 2200 fps with 40.4 grains of IMR 4895 powder, and 2500 fps with 45.0 grains of IMR 4895. The ME at 2500 fps is 2498 ft. lbs. The Sierra ballistics tables show the following trajectory: +2.49" at 100 yards, 0 at 200 yards, and -10.09" at 300 yards. These Sierra loads were develoed using Norma brass and Rem. 9 1/2 primers in a Type 99 rifle with a 25" barrel.
Note: Another article about the 7.7mm Arisaka can be found on the Rifle Cartridge Page.
Copyright 2005 by Chuck Hawks. All rights reserved.