This cartridge was originally developed during late 1960s as a direct rival to the US 5.56×45 M193 carttridge then in use by US Army. Originally it featured a long, low-drag bullet with mild steel core and a hollow cavity in the nose to provide optimum balance, and a laquered steel case. This version was adopted in 1974 and oficially designated in USSR as 5.45mm 7N6. Later on, this cartridge was generally replaced in production in Russia by 7N10 ammunition, which has improved penetration thanks to harder steel core. Other bullet types in the 5.45×39 range of military ammunition include tracers, armor piercing and subsonic cartridges (for use by Spetsnaz troops in silenced AKS-74UB compact assault rifles).
The 5.45×39 is still a general issue caliber in the Russian military and a few of other ex-USSR republics. In most other the ex-Warsaw pact countries this caliber was gradually replaced in service with 5.56×45 NATO ammunition and appropriate weapons.
Designation Bullet weight, g Muzzle velocity, m/s Muzzle energy, J Comments
5.45×39 7N6 3.43 880 1328 bullet with mild steel core
5.45×39 7N10 3.62 880 1400 bullet with enhanced penetration
5.45×39 7N22 3.68 890 1430 armor-piercing bullet with hardened steel core
5.45×39 7U1 5.2 303 239 subsonic, for use with silenced AKS-74UB compact rifle only