This Carlson’s magazine extension (mfr. part no. 04521) adds 12 rounds of capacity to a Remington 870, 1100, 11-87, Versa Max, or V3 shotgun. Confirm your shotgun’s gauge before ordering.

Key Specifications

• Adds 12 rounds to your shotgun’s magazine capacity.
• Fits the Remington 870, 1100, 11-87, Versa Max, and V3.
• Constructed of blued solid steel.
• Includes a spring.
• Includes a base clamp with swivel stud (works with a QD sling swivel, sold separately).
• Includes a high-visibility follower.
• Threaded tube design replaces the factory magazine cap.
• Confirm your shotgun’s gauge before ordering.
• Manufactured by Carlsons.

Frequently Asked Questions

Is this the largest Remington 870 extension Carlsons offers?

It’s the 12-round version; Carlsons also offers 7, 8, and 10-round extensions for the same Remington platform.

What comes in the box?

The extension tube, spring, base clamp with swivel stud, high-visibility follower, and instructions.

Buy the Carlson’s Remington 870 12rd Extension

Shop the Carlsons lineup or browse our full Other Gun Accessories & Parts selection to find the right fit for your firearm.