Own a piece of firearm history from the makers of the world's most battle-proven firearms. The FN 15 Military Collector Series M16 upper receiver assembly is an authentic reproduction of the original, made to FN's and the U.S. military's exacting specifications. A 20-inch, 1:7 RH, button-broached barrel is chrome-lined and chambered in 5.56x45mm NATO. The upper is furnished with a complete M16-style MIL-SPEC bolt carrier group, including a HPT/MPI-tested bolt made from Carpenter 158 steel. A Knight's Armament M5RAS quad-rail and adapter covers finish off the authentic reproduction, making a perfect match for any M16-style build. FeaturesKnights Armament M5 RAS Adapter rail with rail adapter covers20" button-broached, chrome-lined barrel with A2-style compensatorM16-style MIL-SPEC bolt carrier group and HPT/MPI-tested bolt made from Carpenter 158Matech Rear Sight