Bird Gun to Zombie Killer: Upgrading the 870 Pump Shotgun

By Woody published on in News

Many shooters love the Remington 870 pump shotgun in the field, and I have owned many 870s I used for doves, ducks, and bucks. The gun has a basic appeal as a game-getter.

Here’s the 870 in its original form. The author wanted an adjustable buttstock instead of the fixed stock shown, which lead to a sizable upgrade overall.

I have also owned one self-defense version, a Remington Model 870 Express Magnum Synthetic 12 gauge, which I bought for $325 six years ago. The 870EMS is a capable home-defense scattergun by any measure. Mine had a matte-black synthetic-stock, a 3-inch chamber, and 18-inch barrel. It weighed 7 pounds unloaded. The fixed buttstock had a length of pull of 14 inches, a drop at comb of 1.5 inches, and a drop at heel of 2.5 inches, with no cast.

But since I’ve become an AR owner, I love the flexibility of a six-position collapsible stock, so I began looking around for 870 replacement buttstocks. Grazing online at, I found several choices and settled on a Blackhawk! Knoxx SpecOps Recoil Reducing Shotgun Stock for Remington 870 (CTD Stock No. 2-BHK04100-C, $81.19).

Installing the new Knoxx buttstock was easy. Using a ratchet-handle driver with replaceable tips, I removed the Phillips-head screws holding on the existing buttpad, and then switched bits and took out the buttstock screw. I pulled the solid buttstock off. Then, using the supplied long Allen wrench, I screwed the adjustable Knoxx stock onto the gun in less than 3 minutes. Next, I installed the replacement forend supplied with this kit. Putting the forend on took about 10 minutes with an 870 action nut wrench.

At the Range

Next, I tested the stock components for function. I had access to an identical 870 sans modifications, so I could compare the before-and-after guns shot to shot. Firing a range of shells from light 2.75-inch bird loads to 3-inch steel magnums, I immediately liked the Knoxx buttstock. It uses a spring-loaded recoil-absorption system to reduce felt recoil and muzzle rise. The soft, thick rubber recoil pad was 5/8 inch thick, and it noticeably cushioned the blows of the magnums. Of course, being able to adjust the LOP to exactly what I wanted made a big difference in fit. Also, the ergonomic plastic pistol grip with finger grooves improved control for fast follow-up shots. The ribbed replacement forend provided a good gripping surface, though the original forend was fine as well.

Fine Tuning

I later added XS Ghost Ring sights and a Wilson mag extension to really get this 870 where I want it. The Wilson Combat machined-steel two-shot magazine extender (Wilson stock #SGET-RH-2) comes with a magazine spring and high-visibility chartreuse nylon follower. Installing the XS Ghost Ring sight required drilling and tapping my 870’s receiver, which I had done at a local gunsmith shop. Many shotguns are already drilled and tapped, and in that case, the X

Blackhawk Knoxx SpecOps Adjustable

The SpecOps stock uses a spring-loaded recoil-absorption system to reduce felt recoil and muzzle rise

S sights are drop-in installs. Of the components, the recoil-reducing stock offered the most noticeable improvement over the standard version.

On my gun, I probably didn’t need the Wilson mag extension, but if you’re upgrading a shorter 870 tube, that extension increases capacity and adds a front sling-attachment spot. The XS sights are another big upgrade over the basic 870. If you intend to shoot slugs and want to hit what you’re aiming at, I consider them to be vital additions.

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