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

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 RH metric 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, and it ships with a metal thread protector to keep the threads clean when a can isn’t attached. It’s a straightforward, factory-spec upgrade for anyone running suppressed .45 ACP on a Glock 21.

Key Specifications

• Chambered in .45 Auto, the factory-spec caliber for the Glock 21 platform.
• Direct-fit for Glock 21 Gen3 and Gen4 frames, a factory-spec drop-in replacement.
• Cut with a .578×28 RH metric thread pitch to accept a .45-caliber suppressor or muzzle device.
• Ships with a metal thread protector to cap the threads when a suppressor isn’t mounted.

Frequently Asked Questions

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

What thread pitch does it use? It’s cut .578×28 RH, the standard metric thread pitch 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’re not running a suppressor or muzzle device.

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

Order this barrel from our Lubbock, Texas gun shop and we’ll have it ready to ship to your door. Shop the full Glock parts lineup or browse our complete Glock barrels selection.