Palmetto State Armory has become known for making high quality AR15 Modern Sporting Rifles at affordable prices. Offering a wide range of models, everything from basic M4 style rifles with chrome lined military style barrels; to this 16" Nitrided barrel with 11" Keymod rail system. The Upper and lower of the PSA line of rifles are made from high quality 7075-T6 aluminum, Bolt Carrier Group is Milspec full auto style made from carpenter steel with gas key hardened as per Milspec requirements and fastened with Grade 8 screws and properly staked, the PSA BCG is chrome lined and phosphate coated for long term durability. The Barrel on this great smi-auto rifle is made from chrome-moly steel chambered in 5.56x45 NATO 1/7 twist with midlength gas system in a medium barrel contour. The barrel on the PSA 5.56mm Freedom Rifle is also Nitride finished which provides the strength and durability of chrome lining without adding unnecessary material to the inside of the barrel which can affect accuracy out at distance.