This Bear Creek Arsenal AR-15 8.5" heavy parkerized 300 Blackout has a pistol length gas system with a 1:8 twist. Our 300 Blackout parkerized pistol barrels are made from the finest 4150 Chrome Moly Vanadium and precisely rifled for high accuracy at a great price. Use a Bear Creek Arsenal ar barrel in your next AR 15 build and experience superior performance back by a lifetime warranty!All finished barrels go through a 100% inspection process. Inspections Equipment includes CMMs and Air Gauges for the bores as well as visual and machine inspection.Specifications:Magazine Capacity: N/ABarrel Length: 8.5Profile: Heavy BarrelTwist: 1:8Barrel Finish: ParkerizedMaterial: 4150 Chrome Moly VanadiumThread Pitch: 5/8 x 24Caliber: .300 BlackoutFeed Ramp: .300 BlackoutFlutes: Non-flutedGas System: Pistol LengthGas Block System: 0.750Classification: AR Pistol BarrelPlatform: AR-15