He served during WWII as a tank commander. He was seriously wounded in October 1941. He designed his first submachine gun while in the hospital. In 1947, his updated assault rifle, known as the AK-47 (an acronym for "Avtomat Kalashnikov model 1947"), was found to display the highest reliability and most effective fire during arduous competitive tests. In 1949 the AK-47 assault rifle became operational in the Soviet Army.
Later in his career he developed a squad automatic weapon variant of the AK-47, known as the RPK-47 (Ruchnoi Pulemyot Kalashnikova - Kalashnikov's Light Machinegun), and also the PK (Pulemyot Kalashnikova - Kalashnikov's Machinegun), which used a much larger cartridge (the same full-powered rifle cartridge as employed in the Mosin-Nagant rifle). The cartridge was belt-fed rather than magazine-fed. In other respects, it was nearly the same design.