This brand new Colt XM177E2 is a semi-automatic rifle which fires the 5.56mm round. It has a 16″ barrel and grey finish. This includes 1 20-round magazine, fixed carry handle, collapsible metal butt stock, patch, sling, box, lock and manual. This rifle is marked Property of U.S. Govt., Safe/Semi/Auto (fires semi-auto only) and is commonly referred to as the GAU.