"Behind the gas block will be a Government profile tapering to a shoulder and 1.1"" journal .625 gas block. In front of the gas block, the barrel will continue straight to a 1/2x28 muzzle with full shoulder.  Faxon Firearms barrels are the pinnacle of value. Manufactured 100% in-house from cradle-to-grave, these barrels are fully stress relieved, air-gauge tested, and 11 degree target crowned to ensure superior accuracy.  Technical Specifications Barrel Material: 4150 GBQ Steel Barrel Type: Button Rifled  Barrel Caliber: 5.56 NATO* Barrel Twist: 1:8 Barrel Length: 11.5"" Barrel Profile: BIG Gunner Hybrid Barrel Gas System: Mid** Inside Finish: QPQ Nitride Outside Finish: QPQ Nitride Muzzle Thread: 1/2-28 TPI (Threads Per Inch) Gas Block Diameter: .625"" Barrel Extension: M4 Weight: 1.14 lbs Magnetic Particle Inspected! 11-degree Target Crown *As this barrel is likely to be used in full-auto applications, we are opting to stick with a 5.56 chambering to ensure absolute safety for our customers.  **Due to the short dwell of the barrel, the gas port will be larger than most barrels. Customers are encouraged to use an adjustable gas block for optimum functionality. "