Faxon Firearms Duty 5.56mm NATO Rifle Barrel 16inch M4 Profile Carbine Length 1-7 Twist Mag Phosphate Matte. Manufactured in-house in Cincinnati Ohio Faxon barrels are fully stress relieved air-gauge tested and 11 degree target crowned to ensure superior accuracy. Quality is imbued into our barrels from the beginning of the manufacturing process.. We 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. Specifications for Faxon Firearms Duty 5.56 NATO Rifle Barrel: Manufacturer: Faxon Firearms Color: Black Finish: Matte Barrel Material: 4150 CMV Steel Weight: 1.22 lb Package Contents: Faxon Firearms Duty 5.56 NATO Rifle Barrel Faxon Firearms 15A57C16N4P-CL: Duty 5.56 NATO Rifle Barrel 16inch Carbine Length 1-7 Twist Mag Phosphate