5.8×21mm

The 5.8×21mm was developed by Norinco and introduced in 1994 as a Chinese personal-defence cartridge, sized to sit between a conventional pistol round and a full-power rifle round for the same reasons that led NATO armies to adopt 5.7×28mm and 4.6×30mm around the same period. It is a distinct design from China’s other 5.8mm family, the 5.8×42mm rifle cartridge adopted for the QBZ-95 service rifle; the two share a bullet diameter but nothing else, being built for entirely different classes of weapon.

Its bottlenecked, rimless case and small overall length reflect that personal-defence brief: a short, light cartridge intended to be carried and fired from a compact pistol or a submachine gun-sized weapon rather than a rifle, while retaining a bottleneck shape more usually associated with rifle cartridges to seat a small-diameter, steel-cored bullet efficiently. It was developed alongside the Norinco QSZ-92 and the DAP92 machine pistol on which it is most closely identified.

Every dimension in this entry is taken from Wikipedia’s infobox rather than a primary standards document: this is a Chinese military cartridge outside any C.I.P. or SAAMI commercial catalogue, so no free dimensional datasheet exists to check it against, and it is recorded here as estimated rather than verified. The infobox’s own ballistics table lists a 46-grain bullet weight for its steel-cored load, but names its test barrels only as “pistol” and “submachine gun” rather than a length in millimetres, so no velocity point could be recorded for either weapon. No photograph of this cartridge was found across Wikimedia Commons, the Smithsonian’s open collections or DVIDS.