7.62x39 Once-Fired Brass
The 7.62×39mm (aka 7.62 Soviet or formerly .30 Russian Short) round is a rimless bottlenecked intermediate cartridge of Soviet origin. The cartridge is widely used due to the worldwide proliferation of Russian SKS and AK-47 pattern rifles, as well as RPD and RPK light machine guns.
Shortly after World War II, the AK-47 was designed, later becoming the world's most widespread military-pattern rifle. The cartridge remained the Soviet standard until the 1970s. It was largely replaced in Soviet service by the 5.45×39mm cartridge, which was introduced with the new AK-74 rifle, and continues in service with the modernized current-issue Russian Armed Forces AK-74M service rifle, as well as the AK-12 rifle. In the 21st century the 7.62×39mm remains a common service rifle chambering, including for newly developed rifles like the AK-15.