Proof Research AR-15 Barrel Features Proof Research builds this barrel around a carbon fiber wrapped steel liner a construction method that sheds significant weight compared to a traditional all-steel barrel while retaining the stiffness needed for match-grade accuracy. The 1:8 inch twist rate stabilizes a broad range of .223 Wylde bullet weights letting the shooter run anything from light varmint loads to heavier match bullets through the same barrel. Five grooves cut into the bore help maintain consistent engagement with the bullet s jacket for repeatable accuracy shot after shot. At an 18 inch length with a rifle-length gas system the barrel is built to extract the velocity and stability that longer-range shooting demands. A .750 inch gas block diameter keeps the barrel compatible with common AR-15 handguard and gas block hardware simplifying the build process for anyone assembling an upper. The 5/8x24 threaded muzzle accepts a wide range of muzzle devices from brakes to suppressor adapters giving the shooter flexibility in how the rifle is finished. Because carbon fiber barrels resist the heat-induced accuracy loss that steel barrels can suffer during sustained strings of fire this barrel holds its zero better across extended range sessions. The Proof Research AR-15 Barrel in .223 Wylde is available for sale at GrabAGun. Proof Research AR-15 Barrel Specifications Manufacturer: Proof Research Model: AR-15 Barrel Caliber: .223 Wylde Gun Platform: AR-15 Barrel Material: Carbon Fiber Barrel Description: Standard Barrel Type: Rifle Length Barrel Length: 18 Twist Rate: 1:8 Diameter: .750 Grooves: 5 Thread Pattern: 5/8x24 Available At: GrabAGun