ⓘ 7.7×58mm Arisaka. The 7.7×58mm Arisaka cartridge, Type 99 rimless 7.7 mm or 7.7mm Japanese was a rifle cartridge which was used in the Imperial Japanese Armys A ..

                                     

ⓘ 7.7×58mm Arisaka

The 7.7×58mm Arisaka cartridge, Type 99 rimless 7.7 mm or 7.7mm Japanese was a rifle cartridge which was used in the Imperial Japanese Armys Arisaka Type 99 rifle and machine guns, and was the standard light cartridge for the Imperial Japanese Army Air Service, such as the Type 89. The Imperial Japanese Navy never shared weapons or ammunition with the army, instead adopting the 7.7x56mmR, a direct copy of the.303 British round. The cartridge was designed to replace the aging 6.5×50mm Arisaka after seeing the effectiveness of the MG 34 GPMG in action in China during 1937. Due to a lack of materials, the plan to phase out the 6.5 mm Arisaka cartridge by the end of the war was not completed.

                                     

1. Design

While the round chambered by the Arisaka rifle used a rimless case, rimmed and semi-rimmed variants were produced for use in some Japanese machine guns. This machine gun ammunition is more powerful, and the altered rim is meant to prevent it from being chambered in a rifle.

                                     

2. Japanese ammunition

All Japanese military ammunition used gilding metal jackets for the bullets on ball and the Pentaerythritol tetranitrate PETN-filled flat-tipped explosive incendiary, cupro-nickel jackets for tracer and phosphorus incendiary and a brass bullet with steel core for armor-piercing. The bullet type was signified by a colored band over the case mouth.

Late war ammunition can still be encountered.

                                     

3. Modern Loadings

The 7.7×58mm Arisaka, as a sporting cartridge, is suitable for most big game with proper bullet selection.

The 7.7 mm Arisaka uses the same.311–.312" bullets as the.303 British, and the standard military load delivered the same muzzle energy as the.303 British. Factory loaded ammunition and brass cases are available from Norma, Grafs, and Hornady, Sierra and Speer also produce usable bullets. Reloadable cartridge cases are produced by reforming.30-06 brass, or fire forming 8x57mm IS cases. Case heads derived from the.30-06 are slightly undersized and bulge slightly just ahead of the web on firing, while the 8×57mm IS derived cases are slightly short. Normal cases of the correct dimensions also bulge slightly, however, as most Japanese rifles of this era had slightly oversized chambers, intended to allow the bolt to be closed on a round even in a very dirty chamber. Reloading data for.303 British is often used for load development, since the two cartridges are nearly identical in power and size.



                                     

4. 7.7×58mm Type 92

The Type 92 semi-rimmed 7.7 mm 7.7×58mm SR was a machine gun cartridge and was primarily used with the Type 92 heavy machine gun and the earlier Type 89 flexible and fixed air-cooled machine guns used on Japanese Army planes.