The AR-STONER AR-15 9mm Barrel is the ideal balance of function, performance and affordability. Precisely milled from 4150 Chrome Moly Vanadium Steel, this barrel gives your 9mm Carbine a sleek look with the function to match. The 1 in 10" twist provides superb accuracy and different contour options makes these barrels a consistent shooter. Build an AR-15 pistol with the AR-STONER AR-15 9mm Barrel and shut out the competition. Note: Standard1/2"- 28 muzzle devices do not have clearance for 9mm rounds to pass. Prior to muzzle device installation ensure 9mm rounds pass freely through the muzzle device bore.