Gas-operated semi-automatic rifle chambered for .223 or 5.56mm cartridge. AR-180 is civilian version of AR18, which is fully automatic. Simple and efficient rifle that was tested by various governments and found to have potential. Rifle was also manufactured by Howa Machinery Ltd. and Sterling Armament Co. of England. Most common version is manufactured by Sterling. Those built by Armalite and Howa bring a small premium. ArmaLite Costa Mesa production.