The Heckler & Koch HK416 is a gas-operated assault rifle chambered for the 5.56×45mm NATO cartridge. It is designed and manufactured by the German company Heckler & Koch. Although the design is based on the AR-15 class of firearm (specifically the Colt M4 carbine family issued to the U.S. military), it uses a proprietary short-stroke, gas piston system from Heckler & Koch's earlier G36 family of rifles.