With more than 10 million produced so far, the Remington 870 shotgun is one of the most popular shotguns ever made. Considering the 870 has only been in production since 1951, that is quite an accomplishment. In these 60 plus years of production, there have been innumerable variants of the 870 and even more aftermarket parts and accessories allowing owners to truly customize and personalize their shotguns. The Bullpup Unlimited stock conversion kit for the Remington 870 (also available for the almost-as-prolific Mossberg 500) is one of the latest and most innovative shotgun accessories to be had.
The bullpup concept has been around since the early part of the 20th century and involves a system of shortening the overall length of a long gun by moving the action back behind the trigger. With shotguns, there are two modern day examples in the Kel-Tec KSG and the UTAS UTS-15, both of which retail for far more than your standard 870.
If you like this concept and already have a standard Remington 870 or Mossberg 500, then the Bullpup Unlimited kit offers a deceptively simple and economical way to achieve your objective. It takes about 30 minutes to complete the conversion process, and it is fully reversible in about the same amount of time. The matte black stock is made from a tough molded polymer and has a smooth finish. This kit only fits 12 gauge, 2.75- and 3-inch-chambered Remington 870/Mossberg 500 shotguns with a plain barrel and a bead sight. The front end is open, so barrels longer than 18.5 inches will work, as will extended magazine tubes.
Installation is very simple. After you remove the standard stock and pump grip from your shotgun and install the special sleeve for the pump tube, the barreled receiver can be placed inside the lower stock, secured and then the upper stock installed. Both halves are secured with several screws, and it is also easy to install ambidextrous sling attachment points. The kit includes a full-length Picatinny rail on top for mounting optics, as well as removable rails at the front on both sides and along the pump grip.
The kit features a long trigger bar, which works effectively, but as with most bullpups leaves a rather mushy feel to the trigger. The stock completely surrounds your shotgun and comes with its own controls—you won't be able to reach the standard controls on your gun after installation. Make doubly sure the gun is unloaded, because it must be in the "fire" mode when you assemble it, as the Bullpup Unlimited kit has its own AR style grip and safety selector. There is also a trigger-tab safety similar to that found on many polymer striker-fired pistols for added safety.
The action-release is located at the rear of the stock at the bottom on the right side. Loading and pump operation remains the same as on a stock 870. I did find that a very aggressive pump action is required to prevent short-stroking and to ensure spent cases eject properly. The feeding port is enlarged, so it is easy to access and there is an oversize shell deflector above the ejection port, making it easier for left handed shooters to use.
The advantages to a bullpup design is that you keep the same barrel length, stock length, length of pull and functionality of your gun, but radically reduce the overall length. The shorter length makes storage and transportation much easier and significantly improves maneuverability, especially in tight confines. I have fired both the UTS-15 and the KSG and found another benefit is the center of balance is shifted towards the center of the gun, where the pistol grip is located. This actually makes the gun feel lighter and reduces perceived recoil as well as muzzle rise. The effect is the same with the Bullpup Unlimited kit installed.
The overall length of the bullpup conversion is 28 inches—the only thing that would add to it is if you use a barrel longer than 18.5 inches. The new stock does weigh more than two pounds, which adds to the shotgun's overall weight, but because of the shift in balance there is actually less shooter fatigue experienced when handling it.
With the increased popularity of bullpup rifles and shotguns, and the incredible abundance of Remington 870s and Mossberg 500s, the Bullpup Unlimited kit can take your old shotgun and repurpose it to a new tactical role suitable for home defense around tight corners and narrow hallways. MSRP for the kit is $359.