Barrel: 10.5" barrel chambered in 5.56 NATO with a 1/7 twist, M4 barrel extension, and a carbine-length gas system. Barrel is finished off with an F-marked front sight post, quad rail handguard with rail covers, and an A2 flash hider.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. Upper includes Rock River Arms A2 Rear Sight.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 M4A1 lower with HAR-15 Pistol Brace and Classic A2 grip. Black finish. Marked 5.56 NATO.Made in America and compatible with all AR-15 uppers.