(600 yd) Feed system 10, 20, 30, 40 round magazines 50, 90, 100 round drums Sights Adjustable front and rear iron 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