Sincerco Threaded 45 Auto (ACP) Smith & Wesson M&P Handgun Barrel - 5.18in - Black - All pistol suppressors require a threaded pistol barrel. SilencerCo noticed a market need for high quality pistol barrels and we stepped in to offer them. Holding to the same commitment to quality as all of our products, the threaded barrels are tough enough to hold up under the harshest conditions. Made of 416R stainless steel and finished in black nitride (some models remain stainless). For use with a pistol silencer, you will also need a piston (sold separately). Includes Thread Protector Black Nitride Finish .578in x 28 Threaded