The full form of AK–47 is Russian Avtomat Kalashnikova 1947.

he AK-47, officially known as the Avtomat Kalashnikova (Russian: Автома́т Кала́шникова, lit. ‘Kalashnikov’s assault rifle’; also known as the Kalashnikov or just AK), is a gas-operated, 7.62×39mm assault rifle developed in the Soviet Union by Mikhail Kalashnikov circa WWII. It is the originating firearm of the Kalashnikov rifle (or “AK”) family. The number 47 refers to the year it was finished.

Design work on the AK-47 began in 1945. It was presented for official military trials the following year, and in 1948 the fixed-stock version was introduced into active service with selected units of the Soviet Army. An early development of the design was the AKS (Skladnoy, or ‘folding’), which was equipped with an underfolding metal shoulder stock. In early 1949, the AK was officially accepted by the Soviet Armed Forces and used by the majority of the member states of the Warsaw Pact.

AK-47, also called Kalashnikov Model 1947, Soviet assault rifle, possibly the most widely used shoulder weapon in the world. The initials AK represent Avtomat Kalashnikova, Russian for “automatic Kalashnikov,” for its designer, Mikhail Timofeyevich Kalashnikov, who designed the accepted version of the weapon in 1947.

Almost from the moment of its official adoption by the Soviet military in 1949, the AK-47 was recognized as being simple to operate, rugged, reliable under trying conditions, and amenable to mass production. Built around a 7.62-mm round with a muzzle velocity of some 700 metres per second, it had a cyclic firing rate of 600 rounds per minute and was capable of both semiautomatic and automatic fire. A long curved box magazine held 30 rounds, and a separate gas-return tube above the barrel held a piston that was forced back upon firing to activate the mechanisms that ejected the spent cartridge and cocked the hammer for the next round. The AK-47 was manufactured in two basic designs, one with a wooden stock and the other, designated the AKS, with a folding metal stock. Beginning in 1959, the AK-47 was replaced in first-line Soviet service by the AKM, a modernized version fitted with longer-range sights and cheaper mass-produced parts, including a stamped sheet-metal receiver and a plywood buttstock and forward grip.

Despite their obvious advantages, the AK-47 and the AKM were considered by the Soviet military to have problems with accuracy, mainly because of recoil forces generated by the powerful 7.62-mm round and other forces known as blowback that were generated by the weapons’ heavy internal mechanisms. Those problems were partly addressed during the 1970s, when the AKM was replaced by the AK-74, which adapted the basic Kalashnikov design to a smaller 5.45-mm round with a higher muzzle velocity of 900 metres per second. A later version of the AK-74, the AK-74M, was the main infantry weapon of the Russian army into the 21st century.