The AK-47 (also known as Kalashnikov, AK, or in Russian slang, Kalash) is a selective-fire (semi-automatic and automatic), gas-operated 7.62×39mm assault rifle, developed in the Soviet Union by Mikhail Kalashnikov. It is officially known in the Soviet documentation as Avtomat Kalashnikova (Russian: Автомат Калашникова).Design work on the AK-47 began in the last year of World War II (1945). After the war in 1946, the AK-47 was presented for official military trials.