The AR-10 is a lightweight, air-cooled, magazine-fed, gas-operated rifle that uses a piston within the bolt carrier with a rotary bolt locking mechanism. The rifle has a conventional layout; it features an in-line stock, an aluminum alloy receiver and a fiberglass reinforced pistol grip, handguard, and buttstock. While mostly an original design, the AR-10 built upon previously proven concepts. From the FAL it took the hinged receiver system allowing the rifle to be opened for cleaning much like a break-action shotgun. The ejection port cover is similar to that found on the German World War II-era StG44. The bolt locking mechanism is similar to the M1941 Johnson rifle (itself an adaptation of the Browning-designed Remington Model 8 bolt). From the German MG 13 light machine gun, FG 42 and M1941 Johnson machine gun came the idea of the straight-line stock layout. A "straight-line" recoil configuration increases controllability during burst or automatic fire by reducing muzzle climb. The AR-10's method of rotary bolt locking, straight-line recoil, and gas operation enhanced its inherent accuracy.