Faxon Firearms 5.56 NATO 7.5" Government/SOCOM Profile AR-15 Barrel. Machined from 4150 Mil-Spec steel and finished inside and out with black nitride, this 7.5" barrel is button-rifled and designed for the AR-15 platform. Chambered for 5.56 45mm NATO / .223 Rem, it features a 1:8 twist rate, carbine-length gas system, 1/2" 28 TPI muzzle threads, M4 barrel extension, and an 11 target crown. The Government/SOCOM profile blends strength and reduced weight for a durable, maneuverable build ideal for short-barrel ARs, PCC builds, or as an upgrade to your current rifle. Features Barrel Material: 4150 CMV (Mil-Spec) Barrel Type: Button Rifled Caliber: 5.56 NATO / .223 Rem Twist Rate: 1:8 Length: 7.5" (7-1/2") Profile: Government / SOCOM Gas System: Carbine-length Inside Finish: Black Nitride Outside Finish: Black Nitride Muzzle Thread: 1/2" 28 TPI Gas Block Diameter (journal): .750" Gas Block Journal Length: 1.9" Barrel Extension: M4 Weight: 0.89 lbs Inspection: Magnetic Particle Inspected Muzzle: 11 target crown Manufacturer: Faxon Firearms Product Specifications Barrel Length: 7-1/2" (7.5") Barrel Thread Pitch: 1/2" 28 TPI Brand: Faxon Firearms Caliber: 5.56 45mm NATO / .223 Rem Finish / Color: Black (Nitride) Firearm Type: Pistol, Rifle (AR-15 platform) Material: 4150 Steel Models Fit: AR-15