This new Colt M4 Carbine fires the 5.56mm/.223 round. It has a 16" M4 barrel with an overall black finish. This semi-auto rifle has an adjustable stock, a flat top receiver with picatinny rail, and a bayonet lug. It comes with one 30 round magazine, an MOE flip-up rear sight, box, lock, and manual. This is a generic photo.