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This Carlson's magazine extension is a straightforward way to add serious capacity to your 12 gauge Remington pump without any permanent modifications. The blued steel construction holds up well, and the threaded design simply replaces your factory magazine cap. You get everything you need in the box to get running: the extension tube itself, a strong spring, a barrel clamp with an integrated swivel stud for attaching a sling, and a bright orange follower that's easy to spot when loading.
This extension bumps you from a standard 4 or 6 round magazine up to 10 total rounds with 2-3/4 inch shells. That's a practical increase whether you're running competition courses, hunting upland game, or just spending time at the range. The barrel clamp design sits low-profile and stays put without fussing. Real-world testing shows users are running 10 rounds cleanly through their 870s and 1100s without feeding issues once everything is set up.
Thereadiness is genuinely simple: screw it on and you're basically done. The main thing to know is that newer Remington models have small tabs or dimples inside the magazine tube to hold the factory spring cap in place. A quick pass with a file or Dremel knocks those down, then the extension goes on smooth. It takes maybe 10-15 minutes total, and the included instructions walk you through it. On older 870s without those dimples, you're looking at a 5-minute job. Some owners like to sand down the included plastic follower slightly to ensure it glides freely through both the factory tube and the extension.
Carlson's has made choke tubes and shotgun parts long enough to know what works, and this extension reflects that. The blued finish isn't flashy but it holds up, the spring tension is solid, and the swivel stud on the clamp lets you attach quick-detach slings. Runs well behind 00 buckshot, target loads, or anything else you feed it. The overall length sits around 14.25 inches, so it extends past the muzzle on most standard 870 barrels, which is worth measuring on your specific gun.
Yes, but newer 870 Express models have small dimples or tabs inside the magazine tube that need to be removed first. These tabs hold the factory spring cap in place. A quick pass with a file or rotary tool removes them easily. Once removed, the extension threads on without issues. Older police and wingmaster models typically don't have these tabs.
The 10-shot rating is total capacity including one round in the chamber. So if your 870 or 1100 holds 4 rounds in the magazine factory, this extension adds 6 extra rounds in the tube. With 3-inch shells you lose one capacity; with 3-1/2 inch shells you lose two, so plan accordingly if you run magnum loads.
On a 28-inch barrel it typically ends up 1-3 inches shorter than the muzzle. On shorter barrels like 20 inches, it will extend past the barrel. Measure where your magazine tube ends and add 14.25 inches to see how far past your muzzle it will reach. You can always go with a shorter extension if that's a concern.
The orange plastic follower can be slightly oversized and may need a quick sanding to fit smoothly through the factory tube and extension. The spring is well-tuned and works reliably, though some users swap in aftermarket springs if they want different tension. The included hardware is solid and most people run it as-is without issues.
| UPC | 723189045043 |
|---|---|
| Manufacturer | |
| Manufacturer Part Number | 04504 |
| Brand Fit | Remington |
| Caliber/Gauge | 12 Gauge |
| Capacity | 10 |
| Length | 15.8500 |
| Model | |
| Model Fit | 870 |
| Shipping Weight | 0.9125 |
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