On medical leave for six months, Mr. Kalashnikov returned to Kazakhstan and his railroad office. He enlisted his workmates in designing and making a prototype of a new submachine gun, which he presented to a senior official for evaluation.
The gun was dismissed as no improvement on one already in the Soviet arsenal, but its designer was given a new assignment. He was sent to work in a series of military firearms labs, often in secret cities closed to outsiders.
At first, Mr. Kalashnikov and his team of gunsmiths and engineers focused on a gas-operated, semiautomatic carbine, adapting technology used in the U.S. Army’s M-1 Garand rifle and an earlier Soviet version, but their design lost out to one from a rival weapons lab.
Using the same principle — rechanneling the expanding gases from one shot to reload the firing chamber with another cartridge — the Soviet team developed the AK-47, which won the national competition for an automatic rifle.