Definition
The 7.7×58mm Arisaka is a Japanese military rifle cartridge, a rimless, bottlenecked round measuring 7.7 mm in bullet diameter and 58 mm in case length. It served as the standard infantry cartridge of the Imperial Japanese Army during the latter part of World War II.
Overview
Developed in the late 1930s to replace the earlier 6.5×50 mmSR Arisaka cartridge, the 7.7×58mm Arisaka entered service in 1939. It was chambered principally in the Type 99 rifle and later in various Japanese machine guns, including the Type 2 light machine gun. Production continued through the end of the war in 1945, with both domestic and occupied‑territory arsenals manufacturing the round. After the war, limited quantities were produced for surplus markets, but the cartridge is no longer in regular military use.
Etymology / Origin
- 7.7 mm – Refers to the nominal projectile diameter (approximately 0.303 in).
- 58 mm – Indicates the length of the cartridge case.
- Arisaka – Derives from the name of Colonel T. Arisaka, a chief designer of the Japanese rifle family that bore his name. The term “Arisaka” thus identifies the lineage of firearms for which the cartridge was intended.
Characteristics
| Attribute | Specification |
|---|---|
| Cartridge type | Rimless, bottlenecked |
| Bullet diameter | 7.7 mm (0.303 in) |
| Case length | 58 mm |
| Overall length | ≈ 79 mm |
| Standard bullet weight | 10.5 g (162 gr) for early Type 99; later 12.0 g (185 gr) for improved loadings |
| Muzzle velocity | Approximately 760 m/s (2,493 ft/s) with the 10.5 g bullet; up to 800 m/s (2,625 ft/s) with the 12.0 g projectile, depending on barrel length |
| Maximum pressure | ~ 45 ksi (310 MPa) (SAAMI‑equivalent) |
| Primer type | Small‑size boxer |
| Typical firearms | Type 99 rifle, Type 2 light machine gun, Type 99 light machine gun, and converted Type 38 rifles |
| Production period | 1939–1945 (primary) |
The cartridge features a steeply tapered case shoulder and a relatively large powder charge, allowing higher muzzle energy compared with its predecessor, the 6.5×50 mmSR. It was designed for improved terminal performance and better long‑range ballistics, aligning Japanese infantry firepower with contemporary European cartridges such as the 7.92×57 mm Mauser.
Related Topics
- 6.5×50 mmSR Arisaka – The earlier Japanese service cartridge replaced by the 7.7×58mm.
- Type 99 rifle – The primary infantry rifle for the 7.7×58mm cartridge.
- Type 2 light machine gun – A Japanese squad automatic weapon chambered for this round.
- Imperial Japanese Army – The military organization that adopted the cartridge.
- Japanese military small‑arms development – Broader context of Japanese firearm and ammunition design during the early 20th century.
- World War II Japanese ammunition – Overview of ammunition types used by Japan during the conflict.