5.45×39mm in the context of "AK-74"

The 7.62×39 mm (also called 7.62 Soviet, formerly .30 Russian Short) round is a rimless bottlenecked intermediate cartridge of Soviet origin. The cartridge is widely used due to the global proliferation of the AK-47 rifle and related Kalashnikov-pattern rifles, the SKS semi-automatic rifle, and the RPD/RPK light machine guns.

The AK-47 was designed shortly after World War II, later becoming the AKM because the production of sheet metal receivers had issues when first initiated. This weapon is now the world's most widespread military-pattern rifle. The cartridge remained the Soviet standard until the 1970s. It was partly 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 7.62×39 mm remains a common service rifle chambering, including for newly developed rifles like the AK-15.

The two most common assault rifles in the world are the Soviet AK-47 and the American M16. These Cold War-era rifles have been used in conflicts both large and small since the 1960s. They are used by military, police, security forces, revolutionaries, terrorists, criminals, and civilians alike and will most likely continue to be used for decades to come. As a result, they have been the subject of countless comparisons and endless debate.

The AK-47 was finalized, adopted, and entered widespread service in the Soviet Army in the early 1950s. Its firepower, ease of use, low production costs, and reliability were perfectly suited for the Soviet Army's new mobile warfare doctrines. More AK-type weapons have been produced than all other assault rifles combined. In 1974, the Soviets began replacing their AK-47 and AKM rifles with a newer design, the AK-74, which uses 5.45×39mm ammunition.