The AA 12 is a thorough redesign of the Atchisson Assault shotgun invented back in 1972. The current version is a fully automatic, 3-inch 12 gauge with a rate of fire of 300 rounds per minute. It operates via what's known as a "constant recoil" system which is a gas action, in which a large quantity of the expanding gases are bled out of the barrel to drive the bolt back. Unlike most gas guns, where the bolt slams into the back of the receiver, the constant recoil AA 12's bolt is free to travel backward until the gun's action spring slows it, stops it, and returns it forward. The result is a gun with reportedly 10% of the recoil of most 12 gauges - that's an incredible figure, but watch on the video how easily shooters can control the gun, even on full auto.