800 round/min Muzzle velocity 975 m/s (3,200 ft/s) Effective range 600 yd (550 m) Feed system 10, 20, 30 round box magazines Sights iron/optical The AR-15 is a lightweight, air-cooled, magazine -fed, autoloading , centerfire rifle . The original Armalite/Colt AR-15 was a selective-fire prototype submitted for consideration as a military infantry rifle, and is distinguished