Lego minifig compatible Custom SI-Dan Toys AK47s is highly detailed and includes a detachable scope and bayonet. Comes in 3 parts. Also known as the Kalashnikov or just AK. A gas-operated, 7.62×39mm assault rifle developed in the Soviet Union by Mikhail Kalashnikov in the aftermath of World War II. The number 47 refers to the year it was finished. The AK-47s used a long-stroke gas piston above the barrel.