The Glock 21 Gen3/4 .45 Auto threaded barrel (Glock part no. 47740) is a factory black steel replacement barrel built to fit Glock 21 Gen3 and Gen4 pistols. Cut with a .578×28 right-hand thread, it gives Glock 21 owners a direct path to mounting a .45-caliber suppressor or muzzle device without sending the pistol out for gunsmithing. It ships with a metal thread protector to keep the threads clean when a can is not attached. It is a straightforward, factory-spec upgrade for anyone running suppressed .45 ACP on a Glock 21.

Key Specifications

• Chambering is .45 Auto, the factory caliber for the Glock 21.
• It is a direct-fit factory drop-in for Glock 21 Gen3 and Gen4 frames.
• The muzzle is cut with a .578×28 right-hand thread for .45-caliber suppressors and muzzle devices.
• It ships with a metal thread protector that caps the threads when nothing is mounted.
• The barrel is black steel.
• It is a factory Glock barrel, built to factory specification.

Frequently Asked Questions

What Glock models does this barrel fit? It is a direct-fit factory barrel for Glock 21 Gen3 and Gen4 frames.

What thread pitch does it use? It is cut .578×28 right-hand, the standard pattern for .45-caliber suppressors and muzzle devices.

Does it come with anything to protect the threads? Yes. It includes a metal thread protector to cover the threads when you are not running a suppressor or muzzle device.

Buy the Glock 21 Gen3/4 .45 Auto Threaded Barrel, Black Steel

Order this barrel from our Lubbock, Texas gun shop for direct shipping, and browse more Glock barrels to round out a suppressor-ready Glock 21.