Box Magazine-Fed Shotguns: Game Changing Innovations

posted on August 27, 2018

Earlier this year, I wrote a column on this site about the pros and cons of detachable-box-magazine-fed (DM for short) shotguns. At the time there were multiple foreign-made DM guns, but the majority of those guns tended to be built on Kalashnikov or AR-10 patterns of unknown quality and, as such, are not all that appealing to me. I believe that a shotgun, with its formidable recoil, should wear a full-contour stock that greatly helps mitigate recoil and control the gun. At the time, the new Mossberg 590M and Remington 870 DM shotguns had been announced, but were not available for T&E, so I promised I’d report back when I had more info. Well, I’ve spent a couple months shooting and hunting with the Mossberg 590M, and to me, it’s a game-changer. Here’s why:

As succinctly as I can write it, the 590M instantly turns novice shotgun reloaders into experts. With its 20-round mag, it more than doubles the typical pump-action shotgun’s capacity and cuts the time required to load it by roughly 90 percent. Consider this: The fastest competitive shotgun reloaders in the world, using specialized shell holders and the current fastest, “Load-four technique,” can reload eight shells into a tube mag in roughly 5 seconds. This is silly-fast, and impractical for a tactical-loading technique because it’s so risky; one mistake and the entire sequence can go to hell. Jerry Miculek, using a custom “stick-loader” can ram eight shells into his Mossberg 930 JM competition gun in about 3.5 seconds. This too, is also impractical for defensive purposes, because few people want to carry a stick containing eight shells stacked end-to-end, nor pay for the race gun that allows Miculek to load like this. The general standard for mere mortals is to load one shell from a belt loop, pocket or sidesaddle in 1 second. So eight shells would take 8 seconds, if none were fumbled and all shells were pre-staged perfectly on their person.

The very first time I handled and reloaded the 590M, I reloaded 20 shells in 1 second. I can do this time after time, and so can you. Simply drop the old mag while grabbing a fresh one, turn the gun into your work space so you can see the mag well, insert the lip on the front of the mag first, then rock it back to lock it in. It’s so quick and easy that I’m betting 3-gun tournaments will make special rules around these pump-action guns that will dominate the “heavy-metal” division. If they don’t, it’s almost guaranteed that most competitors will switch to the Mossberg. Why not the Remington? Because that gun comes with three- and six-round options, while the Mossberg’s double-stack mags come in five-, 10-, 15- and 20-round versions.

Quite possibly the most-impressive aspect of Mossberg’s 590M—after the sheer speed of it—is its robustness and positive feel. Rather than creating a retrofitted mag well as Remington did (which has its strengths), Mossberg chose to modify its 590’s loading port. First, it plugged the entry way of the mag tube (that means the mag tube is worthless except as a guide for the pump action) with a plastic plug that has a triangular channel cut into it that meshes with the frontal lip of the magazine. The lip must be inserted into this angular cut first, then rocked back to lock much like an FAL-pattern rifle mag. As it’s rocked back, three teeth molded into each side of the magazine fit into corresponding cut-outs on the receiver walls. This grants the mag great strength against forward, rearward and lateral stress. As the mag is rocked back until almost flush with the receiver, a flange on the back of the magazine presses down on a spring-loaded locking mechanism until the flange slips over a lever that locks it into place. This locking mechanism is retrofitted onto the receiver via four pins. It includes dual, ambidextrous mag-release buttons that extend from both sides just ahead of the trigger guard.

In all, the system is simple, fast and nearly foolproof. As made, nearly anyone who is familiar with loading an AK-pattern-rifle will have no problem reloading the 590M swiftly. For shooters with smaller hands, the technique requires the shooter slide his hand up the wrist of the stock and onto the receiver slightly so the trigger finger can reach and depress the mag-release button, but with a little practice this can be mastered as the gun is curled into the work space.

As a bonus, shooters no longer must keep up with individual slug, buckshot or birdshot rounds. Simply mark a mag that’s loaded with one type of shells. Want to transition from 00 Buck to slugs? Simply replace the mag in the gun for another mag, and presto, you have up to 20 slug rounds in 1 second.

As for negatives, there’s only really one. As you’ve probably guessed, being of the double-stacked variety and wide enough for shotgun shells, long enough to hold 20 and containing the monstrous spring and follower necessary to support all of that weight yet still have enough energy to fight gravity and load rounds in the chamber, the mags are big. No, they’re huge. When you first see and feel them, you’ll think of them as an Acme brick. Being so long, these mags (made by Adaptive Tactical) are reinforced with metal screws and ridges of molded polymer, which also adds to their bulk. This means that the shotgun balances differently—it’s heavier, and it becomes much less streamlined than inline, tubular-mag-fed guns. That big mag can certainly get hung up on stuff. Not to mention, a fully loaded 20-round mag weighs roughly 3.4 pounds, alone. Further-more, it’s not much fun to load those 20 rounds, either. The loaded 10-round mag weighs roughly 2 pounds, 2 ounces. The five rounder is ideal to keep on hand for specialized rounds or for hunting purposes where applicable. All magazine sizes that I’ve tested have fed and functioned perfectly.

Despite their size, I became used to all of them very quickly. No doubt their likeness to a 30-round AR-15 mag helped. So, the only real problem at the time of this writing is staging these big mags on the body for defensive use. One will fit into a big back pocket of a pair of blue jeans, but you’d better be wearing a stout belt. You could certainly argue that with one 15- or 20-round mag loaded, you probably don’t need to worry about a spare.

Regardless, in the months to follow, third-party companies will no doubt invent custom-size mag holders specifically for these shotguns. I imagine those that will fit on the upper thigh, belt, small of the back and even the chest will make carrying these large mags and reloading the shotgun easy for not just the Jerry Miculeks of the world. As these shotguns become more accepted and ubiquitous, it is quite possible the aftermarket will provide even more.

So, is the 590M my shotgun of choice at the moment? No, because I happen to be more of a semi-auto guy. (But, 20 rounds! I keep thinking. No doubt a number of problems faced by defensive shotgunners will be solved by the 590M). Scuttlebutt on the street hints a 930M version is coming, so I’m ready for the game to change yet again.


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