Faxon Firearms Flame Fluted AR-15 22 ARC Threaded Barrel. 5R is a hybrid rifling with lands opposite grooves and reduced sharp angles that reduces jacket deformation increasing velocity and easy cleaning. Chambered for 22 ARC a high performance cartridge that the 5R rifling takes full advantage of. Each barrel is also fully and individually MPI tested for safety. After rigorous testing the barrels are Nitride treated inside and out locking in the bore improving barrel life and keeping the elements at bay. The extension is coated in Nickel Teflon which maintains incredible dry lubricity corrosion resistance and with the coating tightens up fit between the extension and receiver. Specifications for Faxon Firearms Flame Fluted AR-15 22 ARC Threaded Barrel: Manufacturer: Faxon Firearms Finish: Nitride Caliber: .22 ARC (Advanced Rifle Cartridge) Barrel Length: 20 in Barrel Profile: Flame Fluted Additional Features: Button Rifled 1-07in. Twist Package Content Faxon Firearms Flame Fluted AR-15 22 ARC Threaded Barrel