SilencerCo AC1757 Threaded Barrel 40 Smith & Wesson This is a Silencerco replacement barrel for the for Glock 23 chambered in 40 Smith & Wesson. SilencerCo Threaded pistol barrels are precision machined from heat treated 416R stainless steel. These barrels feature a durable, corrosion resistant matte black Nitride finish. The barrel features a 1:10" twist rate, and this particular barrel is threaded 9/16"x24.