Barrel: A proprietary blend of Hammer forged chrome molly vanadium made by FN that is referred to as "Machine Gun Steel" by virtue of its use in FN's M249 and M240 weapons. The hammer forging process work hardens the steel, making it more durable. In addition, the chrome process for the bore allows for a lining almost twice as thick as a standard M16 for enhanced durability. Chambered in 5.56 NATO, with a 1:7 twist, M4 barrel extension, and a mid-length gas system. The special A2 light profile barrel allows for better balance and portability over the standard A2 profile and is Mil-spec phosphate coated. Barrel is High Pressure tested, and Magnetic Particle inspected, to ensure quality and dependability, and is finished off with a PSA 13" Quad Free Float Rail, .750" low-profile gas block, and a pinned and welded A2 flash hider. The pinning and welding make the flash hider a permanent part of the barrel which brings it to the legal length.Upper: Forged 7075-T6 A3 AR upper is made to MIL-SPECS and hard coat anodized black for durability. Featuring machined T marks, and a mil-spec finish. These uppers are made for us right here in the USA by a mil-spec manufacturer.