Barrel: 16" barrel chambered in 5.56 NATO, 1:7 twist, M4 barrel extension, and a mid-length gas system. The Barrel is finished off with a Geissele .750" diameter Super Gas Block that is pinned to the barrel, A Geissele Super Modular MK14 M-Lok 15" Rail, and a Sabre compensator This barrel is made especially for Palmetto State Armory by FN Manufacturing using their proprietary blend of hammer forged chrome molly vanadium 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. Upper: Forged 7075-T6 A3 AR upper is made to MIL-SPECS and hard coat anodized black for durability. These uppers are T-Marked engraved. Bolt Carrier Group: Father's of Freedom BCG by Microbest with Sprinco Extractor Spring and Carpenter 158 MP Bolt. Lower: Palmetto State Armory complete Sabre-15 lower with black B5 Sop-Mod stock and B5 grip. Black finish. Marked multi caliber. Comes Standard with Springco Buffer Spring, Battle Arms Development Pivot/Takedown Pins, Sabre 2-Stage DLC Trigger, JP Reduced Power Springs, and Anti-Walk Pins. Made in America and compatible with all AR-15 uppers.