Review: Mossberg 590 Shockwave

posted on August 21, 2017

The Mossberg 590 Shockwave is pictured above with a collection of Aguila MiniShells.

Plenty of times I’ve been asked what I think of a shotgun affixed with a pistol grip stock. My answer’s typically gone something like this:

Dear Sir or Madam,

Pistol-grip shotguns have some niche uses, like for fishermen looking to subdue unruly sharks before dragging them aboard, or for SWAT team door breachers who need a shotgun’s blast to derail steel hinges. I’m sure there are some other admirable uses, but for wingshooting a pistol-grip shotgun is just ahead of a claw hammer for usefulness. For home defense, it isn’t much better.

Here’s why: Consider that a 7.5-pound shotgun stoked with a magnum load of 00 buck produces roughly 30 ft.-lbs. of recoil energy. (Compare that to a .223’s 3 ft.-lbs. or a .308 rifle’s 10 ft.-lbs. of recoil energy.) If you fail to use your shoulder, precious cheek and both hands to control its kick, a shotgun is not only difficult to shoot swiftly and accurately, it can be downright painful and even cause injury if your technique falters. And that’s for full-size guns.

If you reduce the stock length by substituting it for a pistol grip (and then shorten the barrel to match) you’ll subsequently drop the shotgun’s weight to 5 pounds. That’s dandy, except when you consider that in doing so recoil is increased to 50 ft.-lbs. (Compare this to a .416 Rigby elephant rifle that produces 55 ft.-lbs.) Then, when you place 90 percent of this recoil on your trigger hand, scarcely a full box of shells is required to make the 1911 pistol in your closet a hell of a lot more attractive. Recoil with any shotgun, but especially one wearing a pistol grip, is a reasonable and serious concern.

Next is the little issue of accuracy. Because of the added recoil factor, pistol grips should not be held up to the face where they can be aimed—unless you particularly like nosebleeds. Therefore, they’re best controlled by firmly clinching the trigger hand to the waist or outside of the pelvis bone. But fired instinctively from the hip at distances greater than about 5 yards, these guns are about as accurate as bad guys in any low-budget action movie. Fact is, a shotgun’s pattern fired at home-defense distances only spreads a few inches. There’s more.

Typically, pistol-gripped guns are created with compactness in mind, so their magazine length mirrors their short barrel. Most hold five rounds, max. While I’d like to think five rounds of double-aught would be enough to deliver bad news to any evil-doer, I’d also like to think that I’m tall, dark and handsome. In reality, shell capacity is like cash at Christmas: The more the merrier.

So keep your full-size buttstock.

I’ve just spent a third of this story telling you why I think pistol grip shotguns are little more than “stunt guns” best saved for Hollywood sets rather than defending your home in the real world. In most scenarios, you’d be better off with a full-size shotgun, a carbine or a legitimate handgun. So when the new Mossberg 590 Shockwave model surfaced at the 2017 SHOT Show in Sin City, I rolled my eyes. Today, however, due to a few parallel inventions, my rather strong views are…evolving.

The Mossberg 590 Shockwave is a shortened version of Mossberg’s venerable Model 590 pump. Its action is battle-proven-reliable and needs little explanation. Like always, the thumb safety is located on the tang so it’s innately ambidextrous. The gun features Mossberg’s trademark deeply grooved fore-end that allows easy cycling, even when the hand is made slippery by the sweat of battle. The fore-end features a nylon strap that prevents the hand from slipping in front of its stubby muzzle. I like it.

At only 14 inches, the Mossberg 590 Shockwave’s barrel is shorter than what you’re used to seeing on a shotgun, but is nonetheless legal for purchase by the average consumer. Check restrictions in your locality to be sure.

Rather than a buttstock or even a typical pistol grip, however, the Mossberg 590 Shockwave features an elongated, hard polymer “bird’s head” grip that at first blush seems bizarre in that it only serves to reduce what little purchase a normal, rubbery, 90-degree pistol grip would lend. But it turns out that Mossberg knew what it was doing; the bird’s head “Raptor” grip made by Shockwave Technologies serves a specific purpose, and that purpose is to make the firearm measure more than 26 inches in overall length, which is one key to the gun remaining classified as a “firearm” and therefore not requiring an NFA (National Firearms Act) stamp for purchase—despite its 14-inch barrel. That said, I wish it were made of soft rubber that’s easier to hold.

Previously, most people—including attorneys and this writer—thought that a 14-inch barrel would unto itself make the shotgun an NFA item, however, the introduction of several new firearm designs has brought significant attention to the interplay of several key definitions in federal firearm law. The ATF verified the legality of these arms via official letters it sent to several makers. (Check out Mossberg’s letter on its website.) The lack of NFA requirements on these firearms, when combined with the recent ATF clarification on pistol arm braces, has led some boutique gun makers like Black Aces Tactical and others to develop innovative new firearm designs by creating shotshell-firing arms that were never intended to be fired-from-the-shoulder guns. Basically, the layman’s version of the law goes like this, as quoted from Black Aces Tactical on its Facebook page:

“[The Short Barrel DT] never had a stock, so it will not be a short-barrel shotgun…so it will never be an NFA item. It’s not an ‘Any Other Weapon’ because it’s over 26 inches long. And since it has a forward grip required by its design to function [and also lacks a rifled bore], it cannot be a pistol. Thus, if it’s not an SBS, not a AOW and not a pistol, it can only be a ‘firearm,’ and a firearm can be transferred to qualifying individuals in most states with a standard 4473 and background check.”

Black Aces Tactical claims it received the letter affirming its Short Barrel DT wasn’t an NFA item long before Mossberg did, and I believe that to be true because its guns have been out longer. Who was first is insignificant to consumers, but the ATF letter is significant in two ways. First, it allows citizens in good legal standing aged 21 and older to buy the Mossberg 590 Shockwave and similar guns without the paperwork hassle and the $200 cost of an NFA tax stamp. Secondly, it warns consumers that the guns’ definitions could change depending on the manner in which they are used.

“Please note,” wrote the ATF, “that if the subject firearm is concealed on a person, the classification with regard to the NFA may change.”

Also of note is that the Mossberg 590 Shockwave’s legal definition, and subsequently its legal status, would definitely change if the end user altered the gun by adding a buttstock or making other modifications. Mossberg warns consumers of this in a letter included with each gun. In short, don’t mess with the damn thing.

Mossberg released the 590 Shockwave with its 14-inch, cylinder-bore barrel and bird’s head “Raptor” grip that make the gun 18- to 20-inches shorter than typical full-length shotguns, but also even less controllable than typical pistol-grip scatter-guns due to its elongated, darn-near English-style grip. The Shockwave holds four rounds of painful 3-inch mags or five 2 3/4-inch shells.

(l.) The shell carrier requires an adapter to function with Aguila Minishells. (r.) With the Mini-Clip installed, the Mossberg 590 Shockwave functions just fine with Minishells.

Awesome! I thought as I left SHOT. Mossberg has created the perfect gun for nobody except Mel Gibson in “Mad Max 15.” Nonetheless, I was sure some folks would buy this “mini-pump,” and I even admitted it has a certain cool factor to it, but I also remembered all the reasons why I think pistol grips (which, technically, this isn’t) are a bit too “Planet of the Apes.”

But now, thanks to good, old-fashioned American capitalism, a few new products have emerged that, when used in conjunction, have rescued the Shockwave from the stinking paws of ridiculousness.

First, the Aguila Ammunition company of Morelos, Mexico, began selling 1 3/4-inch shotshells it calls the Minishell. Aguila offers 7 1/2 shot, slug, No. 1 buck and No. 4 buck. In limited situations, it’s a viable concept for home defense. Here’s why.

(l.) A tough, flexible strap keeps the off hand well-positioned on the slide. (ctr.) The molded rubber Mini-Clip and Minishells transform the Shockwave. (r.) The Mossberg 590 Shockwave can handle 3-inch, 23/4-inch and (with the Mini-Clip adapter) Aguila Minishells.

Driven at 1,205 fps, a
58-ounce load of No. 4 buck delivers seven, .24-caliber pellets that combine for roughly 875 ft.-lbs. of energy at the muzzle. That’s more than twice the energy of a .45 ACP. Yet, because of its reduced payload, a Mossberg 590 Shockwave fully loaded with these shells produces about 10 ft.-lbs of recoil energy compared to the 30 ft.-lbs. of a 2 3/4-inch No. 4 buck (1,205 fps, 1 1/2-ounce payload) fired from the same gun. Sure, it also produces less than half of the 2 3/4-inch shell’s energy, but keep in mind that shotgun shells were originally designed for hunting and are therefore more powerful than needed for ranges merely spanning the bedroom.

As proof of shotgun shells’ original purpose, I remind you of the term “buckshot.” Most deer are not taken at 2 yards, but rather closer to 50. Slugs are good out to 200 or so. At these hunting ranges, the shells need to hold as much powder and lead as practical so they can deliver lethal energies across a wheat field. They also kick like hell. But at 7 yards and closer, Minishell energies are ample. And, as a byproduct of the shells’ length, shotgun magazines can hold nearly twice as many rounds. The Shockwave holds eight in the mag plus one in the pipe. I like that.

While these midget shells function just fine in Winchester 1300 pump shotguns, there was only one problem that I experienced when I fired the Minishells in the Shockwave: They do not function in it. I’m not keen on using a single-shot for squirrel hunting, much less defending my family from attack.

Recognizing the Minishell’s advantage—and tragic flaw—a small company from Texas called OPSol provided a solution. The company’s Mini-Clip is a half-ounce plug of molded rubber that wedges into the shell-receiving area of a Mossberg 590 receiver to effectively shorten it. Basically, the 590’s shell carrier is skeletonized so that the bolt can ride in-between it even as the carrier lifts to raise a fresh shell into battery. But, this means that any shell shorter than about 2 1/2 inches will fall through its open middle rather than be carried into battery. The Mini-Clip provides a false back wall for the Minishell, as it is released from the magazine, so it rides farther forward in the receiver to be captured by the carrier, rather than falling through it. From there it’s sent into the chamber normally.

I’ve shot a couple hundred Minishells through the Mossberg 590 Shockwave with this stupidly simple rubber plug in the shotgun, and it works. While I don’t suspect it’ll last forever because it’s only rubber, I’ve had no malfunctions so far. Best of all, it takes 5 seconds to install, without tools.

With it, the Mossberg 590 Shockwave effectively becomes a 26-inch pistol-grip shotgun that’s easy to wield and stash in tight places. It weighs 6 pounds fully loaded. Its recoil is controllable and it holds nine rounds of reduced-power No. 4 buck. Now, if only I could hit the broad side of a bad guy in the dark with it while shooting it from the hip…

(l.) The Mossberg 590 Shockwave is drilled and tapped, so the brass bead sight can be easily augmented. (ctr.) Breaking at less than 6 pounds, the trigger is satisfactory. (r.) Safety placement is similar to Mossberg shotguns, and is ambidextrous.

All modern Mossberg 590s are drilled and tapped for scopes. So, I installed a Picatinny rail on which I mounted Crimson Trace’s Rail Master Pro. This wonderful piece of gear weighs only a few ounces, yet contains a green laser beam and a 100-lumen flashlight. It’s just about the perfect complement to this mini-pump, and here’s why.

The only accessories I place on my home-defense shotgun are a flashlight and possibly a side-saddle to carry more shells. A weapon-mounted light is especially important on a shotgun because unlike a handgun, shotguns are best carried and certainly fired using both hands. This means that in a home-defense situation—likely to occur at night—you’ll need a flashlight, yet you won’t have an extra hand to use it.

So, mount a light on your shotgun. And if you’re going to add the weight and batteries of a flashlight, you might as well add a laser to it if it’s not going to make the gun any more cumbersome. Turns out the laser is also a game-changer.

I was skeptical of lasers on shotguns at first, but after extensive testing, I’ve found they make for incredibly fast and accurate shooting. Plus, your situational awareness is enhanced because you can keep your head up, eyes focused ahead and on the target when you shoot.

A laser’s usefulness is compounded when we are talking about a pistol-grip shotgun that would otherwise be merely pointed from the hip, approximately 2 feet below your natural line of sight. Therefore, it makes hip shooting a viable technique.

So now, my Mossberg 590 Shockwave has morphed into a 26-inch shotgun-like firearm that can deliver nine rounds of No. 4 buck with minimal recoil and pinpoint accuracy even while shooting from the hip at night. It weighs roughly 6.3 pounds fully loaded and with the light. Best yet, the gun itself costs less than $400. Add $15 for the MiniClip. The Rail Master Pro is expensive at $350, but there are less-expensive options from other manufacturers.

Suddenly, the Shockwave is now a serious arm that’s also great for vermin like rabid skunks, attacking rattlesnakes and other critters. It’s perfect for boats and for travel, as it can be kept in a car and fits into many smaller cases for (unloaded) transport.

What’s more, recently my 71-year-old mother requested I help her find a gun for home defense. She doesn’t really like pistols because she doesn’t practice with them enough to master the controls, her petite hands are too slight to rack most slides and she’s never been comfortable shooting them anyway. But she likes shotguns; she shot them when she was younger, and she wanted to give one a try. So I pulled a few shotguns from the safe and handed them to her.

I immediately noticed that she struggled to hold the full-size shotguns to her shoulder for more than a few seconds. Nearly all shotguns, including 20 gauges, are simply too heavy for her to shoulder and maneuver with any dexterity. Recoil on her frail body and face is punishing. So the only way she found that a full-size shotgun can work for her is by holding it at the hip with the stock clinched under her elbow. Then I handed her the Mossberg 590 Shockwave, and it made her day.

We found she could hold it with one hand placed between the action and fore-end so her other hand is free to use the phone or whatever. Using the laser she can shoot it accurately, and with the Aguila loads, it doesn’t hurt her. Solution found, and we weren’t the only ones to find it.

(l.) A bird’s head grip on the Mossberg 590 Shockwave doesn’t provide a lot of purchase, but it does contribute to the 26-inch overalllength requirement. (r.) The magazine cap incorporates a swivel stud for those who would like to install a sling.

At this past NRA Annual Meetings and Exhibits in Atlanta, GA, Remington launched its own version of a mini-pump. The Model 870 Tac-14 is almost identical in function and uses the exact same Raptor grip as the Mossberg 590 Shockwave. Unfortunately, the Minishells do not function in it and OPSol cannot make a simple MiniClip for it without Remington doing some retooling on the 870’s shell carrier. Regardless, I rather suspect other shotgun makers will soon join the mini-pump firearm mania.

Only last year I was poking fun at pistol-grip shotguns. However, I, like you, dear reader, withhold the right to change my opinion. I doubt the Shockwave will replace my full-size VersaMax Tactical as my bedside shotgun of choice, but it has sure found a niche for the times and places where a 4-foot-long shotty just won’t cut it. Plus, the mini-pump makes me feel a bit like Arnold in “Terminator 2” when I strap it to my back, climb aboard my motorcycle and say, “Hasta la vista, baby!”


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