Remington Detachable-Mag 870 DM

REMINGTON'S MODEL 870 DM MAGPUL CAN KEEP UP

Shotguns have an image problem. For any student of the gun, shotguns are regarded as the most versatile class of firearm conceived, despite being outranged by metallic cartridges. And while shotguns don’t ride the short bus, they definitely don’t sit in the back with the cool guns.

Before anyone gets religious on the subject of shotguns versus carbines versus handguns for home defense, we’ll point out that tactics aren’t math, and there’s no universal best answer to that question. The best answer for you is to choose a reliable, accurate platform optimized for your real estate and get proficient with it.

For established rifle and pistol shooters, the reasons to hate on shotguns are myriad; sore shoulders, the limited capacities of tubular magazines, shorter ranges, the need to learn a new manual of arms, and slow reloads.

When it comes down to it, though, it’s that last point that really turns off defensive shooters who face uncertain situations. That uncertainty drives the need to keep a firearm topped off and ready to finish a fight. So the best way to improve a shotgun is to make it easier and faster to load. Detachable box mags are one answer.

Flannel-clad upland types will be pissed if they fail to quail. But, since they aren’t using the shotgun to defend themselves, their team or their family, they aren’t worried about running their double-barreled heirlooms dry. No. Feeding a shotgun is a perennial concern in the tactical realm, ergo the emergence of so many off-brand and imported box-mag shotguns over the years. The fact that few of those designs stick around for more than a half-decade tells us how hard it is to make a reliable box-fed, semi-auto shotgun.

This brings us to Remington’s 870 DM.

When brainstorming a detachable box-mag shotty team Green’s engineers skipped the autoloader issues entirely and chose to base its entry on the venerable Model 870 platform. Doing so bypassed a host of issues that plague semi-auto, detachable magazine shotguns: timing, ammo selection, and sensitivity to shouldering, to name a few.

“Shotguns have been magazine-fed before,” says Remington’s program manager Dan Cox, “but the important thing to us was that ours actually worked. Because most magazine-fed shotgun systems out there are incredibly unreliable.”

He says the reliability issues faced by DM shotguns aren’t necessarily the fault of poorly engineered actions, but rather asking those actions to feed such a wide variety of shells.

So the shotgun’s greatest asset became its greatest engineering challenge when designing the 870 DM magazine. Looking at the range of shells a reliable shotgun is asked to swallow, you’re starting with a polymer body that’s easy to deform and deflect. Then you’ve got a rimmed cartridge, which is a pain to stack. Add the variations of acceptable tolerances in SAMMI cartridge lengths. Plus, there are shell weights from heavy 3-inch magnums down to really light 2 3/4-inch loads. Add different nose weights and payloads and it becomes clear why a reliable DM shotgun is a rarity.

The 870’s pump action is incredibly reliable right off the bat and adding a DM simplifies the action further. A box mag presents shells to the bolt in a straight line instead of taking it on the zigzag journey from tube to lifter to chamber that happens in a tube-fed shotgun.

“We’ve compared huge data sets shooting thousands of rounds each through tube 870s and 870 DMs to create statistically relevant data,” says Cox, “and I can tell you that, mathematically, the DM is actually more reliable than a standard 870. It’s a small amount, but statistically it’s more reliable.”

IT'S COMPLICATED

At first glance, the 870 DM looks like any other 870, but on closer inspection you’ll notice that funky-looking bolt with the collapsible tail shroud. Then, you’ll see that big ejection port. And it’ll dawn on you, as it did for us, that Remington used the Super Magnum action as the basis for the 870 DM. The engineers needed more space in the action to allow feeding from the magazine’s hooked lips, and they got that room by using the larger action size. Despite the bigger action sized for 3½ behemoths, it’s still only going to run 12-gauge 2¾- and 3-inch shells.

For guys thinking of calling Remington to ask about a conversion kit for their 870s (Cox says there’ve been more than a few of these calls … ) know that the road to a DM is more complicated than just bolting on a magwell. Aside from starting with a Super Magnum action, the bolt used in the DM has a stripper guide screwed to it to strip rounds from the mag. On the action side, there’s a bolt for the front magwell screw, and the guide block below the chamber mouth is cut to accept the 870 DM’s unique feed ramp.

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