The Tiger Rock Inc. BRPIS-MICRO 5.56 NATO 5" Pistol Length Barrel offers exceptional strength and accuracy for your AR-15 setup. Designed to enhance both performance and reliability, this barrel features a 1:5 5R twist and a Micro Pistol gas system, ensuring consistent cycling and precision shooting. Length: 5" Pistol Caliber: 5.56 NATO Twist Rate: 1:5 5R Gas Block Diameter: .750" Thread Pitch: 1/2"x28 Material: 4150 Chrome Moly Vanadium Finish: Black Nitride Proudly made in the U.S.A. Fits AR-15 Platforms Enhance your shooting experience with this meticulously crafted barrel.