"The Faxon Gunner profile is a blend of two of the best performing profiles of all time, Gov't and Pencil.  Proving that every once and awhile, the Government can do something right, the Gunner's profile from the extension to the gas block mimics that well-known taper. From there, innovation takes over and the Gunner moves to a .625"" gas block journal and our famed pencil profile out front. Removing the weight from the front of the barrel ensures maximum versatility and keeps material to the rear to maximize heat resistance and mitigate whip. Technical Specifications Barrel Material: 4150 CMV Steel Barrel Type: Button Rifled  Barrel Caliber: 5.56 Barrel Twist: 1:8 Barrel Length: 16” Barrel Profile:  GUNNER Barrel Gas System: Mid Inside Finish: Nitride Outside Finish: Nitride Muzzle Thread: 1/2-28 Gas Block Diameter: .625"" Gas Block Journal Length: 1.9"" Barrel Extension: M4  Weight:  1.37  lbs Magnetic Particle Inspected! 11-degree Target Crown"