Faxon Firearms SOCOM, 1:8 Twist Barrel, 556NATO, 16, Mid Length Gas System, Fits AR-15, Nitride Finish, Black 15A58M16NSQ Quality is imbued into their barrels from the beginning of the manufacturing process. They start with the best materials, either certified 4150 Mil-Spec steel or 416-R Stainless. From there, each barrel goes through a battery of tests at each operation until finished in Nitride and final inspected. All barrels are individually checked for headspace with precision PTG gauges.