Proof Research AR-15 Barrel Features The Proof Research AR Barrel is built with a carbon fiber wrapped construction that sheds weight from the front of the rifle while keeping the barrel stiff under heat and repeated firing. Chambered in 6mm ARC with a 1:7.5 twist rate it is matched to the heavier bullets that make the cartridge effective at extended range. The standard contour barrel measures 14.5 inches with an intermediate-length gas system giving builders a balanced platform for mid-length AR-15 configurations. A 5-groove rifling pattern and a .750 inch gas block diameter keep the barrel compatible with common AR-15 handguards and gas block hardware. The barrel is threaded 5/8x24 at the muzzle ready to accept a compensator muzzle brake or suppressor mount without additional machining. At 1 lb 12 oz it is dramatically lighter than a comparable steel barrel reducing the overall weight of a 6mm ARC AR-15 build for easier handling in the field or at the range. The reduced weight at the muzzle end also improves offhand balance and makes faster follow-up shots more manageable. The Proof Research AR Barrel is available for sale at GrabAGun for AR-15 shooters looking to upgrade to a lightweight accurate carbon fiber barrel in 6mm ARC. Proof Research AR-15 Barrel Specifications Manufacturer: Proof Research Model: AR Barrel Caliber: 6mm ARC Barrel Length: 14.50 Barrel Material: Carbon Fiber Barrel Description: Standard Intermediate Length Gas System Twist Rate: 1:7.5 Gas Block Diameter: .750 Grooves: 5 Thread Pattern: 5/8x24 Gun Platform: AR15 Weight: 1 lb 12 oz Available At: GrabAGun