7×58

7×58, more commonly written 7.7×58mmR, is a Japanese rimmed rifle cartridge developed for the Imperial Japanese Army. The designation indicates a caliber near 7.7 mm and a case length of 58 millimeters; the cartridge uses a rimmed case and a bottleneck design suitable for bolt-action service rifles and early machine guns. It is distinct from other 7 mm rounds such as the Mauser 7×57.

Design and dimensions

The 7×58mmR is a heavy, bottleneck cartridge intended for a relatively powerful 7.7 mm projectile. It fires a full‑metal jacket bullet typically in the vicinity of 170–180 grains. The overall cartridge measures roughly 75–80 millimeters in length, with a pronounced rim to aid extraction in early repeating actions. It was designed for use with smokeless powder and was produced in several loading variations for ball, tracer, and armor‑piercing needs.

Service history

The cartridge became a standard for late‑World War II Japanese small arms, most notably in the Type 99 rifle and the Type 92 heavy machine gun. It represents Japan’s shift to a higher‑velocity 7.7 mm round to improve range and effectiveness compared with earlier smaller‑caliber Japanese service rounds. After World War II, large stocks of 7×58 ammunition persisted in surplus markets and several postwar users encountered or utilized this round in limited capacities.

Variants and ammunition

A range of ball, tracer, and sometimes armor‑piercing variants were produced for the 7×58mmR to support infantry and vehicle‑mounted weapons. As with many WWII-era cartridges, water‑damaged or corroded rounds are encountered in some archives and collections.

See also

7.7×58mmR and related 7 mm Japanese Rimmed cartridges.