Tiger Rock Threaded Barrel 5.56 NATO 7in Pistol Gas System 1-8 Twist 1/2x28 Thread Pitch Black Nitride Black Small. Specifications for Tiger Rock 5.56 NATO Threaded Barrel: Manufacturer: Tiger Rock Fabric/Material: 4150 Heat Treated Chrome Moly Steel Caliber: 5.56x45mm NATO Threads per Inch: 1/2x28 Features of Tiger Rock 5.56 NATO Threaded Barrel Fits: AR-15 Package Contents: Tiger Rock 5.56 NATO Threaded Barrel What firearm models does the manufacturer say Tiger Rock 5.56 NATO Threaded Barrel is compatible with? The manufacturer says that Tiger Rock 5.56 NATO Threaded Barrel is compatible with AR-15Tiger Rock BRPIS-N: Threaded Barrel 5.56 NATO 7in Pistol Gas System 1-8 Twist 1/2x28 Thread Pitch Black Nitride Black Small