The USAS-12 is a gas-operated, semi-auto weapon which is designed to provide sustained firepower in close-combat scenarios. It accepts detachable 10-round box magazines or 20-round drum magazines. Both types of magazine are made of polymer, and drum magazines have their rear side made from translucent polymer for quick determination of the number of shot shells left. It has a range of 40m. It uses a gas system located above the barrel, with more or less conventional rotating bolt locking. The interesting feature, borrowed from Atchisson designs, is the long bolt overtravel, which results in relatively low peak recoil and low rate of fire, which is essential for weapon firing powerful 12 gauge shells. USAS-12 is an ambidextrous weapon, having two ejection ports on each side of the receiver, and two slots on the forearm for cocking handle. The ejector on the bolt and the cocking handle could be easily set to operate either side of the gun, depending on the present shooter needs and preferences.