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[Review] Mossberg 590M Shockwave: Magazine-Fed Freedom

Is it useful? The Mossberg 590M is the mag-fed version of the classic 590 shotgun with a Shockwave grip. We review its reliability, accuracy, & more.

What’s better than your standard NFA defying Shockwave 590?

The Shockwave 590M, the M, standing for the magazine. The madmen at Mossberg took a fun gun and made it more fun via the addition of a 10 round magazine. Oh, but that’s just the magazine it comes with.

Freedom Huddle

Table of Contents


Introducing the M Series

The M series of Mossberg’s guns isn’t just the Shockwave, but two models of actual 590 Shotguns. They premiered at SHOT Show 2018 and the Shockwave variant was released just a few months ago. Mossberg premiered the M series with 5, 10, 15, and 20 round magazines.

Shockwave 590M (11)

(Re)introducing the Shockwave

The Shockwave itself is already an NFA defying firearm.

This weapon is a 12 gauge, pump-action, firearm that is totally not a shotgun. By US law the Shockwave is just an “other firearm”, and because it’s not a shotgun it can have a barrel shorter than 18 inches as long as it has an overall length of 26 inches.  

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American gun laws can be an odd assortment of nonsense, but sometimes they work out well for us and the Shockwave worked out well for us. It’s a fun gun and its inspired multiple models, including some from Remington, Charles Daly, and even semi-auto AK pattern variants.

Shockwave 590M (6)

I love shotguns, so naturally, I love these 12 gauge firearms. Their NFA defying features make me giddy and I love the challenge they present to me as a shooter.

The Freedom Intensifying Magazine

The M Model is something that’s both cool and somewhat ridiculous. The original Shockwave is a lithe, lightweight gun. The Shockwave 590M is a bit bigger and heavier with the magazine breaking up the relatively small profile of the gun.

The Shockwave does grant you the substantial increase in capacity. The stock ten round magazine doubling the capacity, and the 15 and 20 rounder adding even more ammo capacity to a small platform. These magazines are double stacks and compact in length, but not width.

Shockwave 590M (5)

They are meaty, and the 10 rounder weighs about a pound unloaded. They are made by Adaptive Tactical, a company known for their shotgun magazine conversions.

The magazines are pricey, with the 15 and 20 rounder costing in excess of a hundred bucks at most retailers. I will say they are well made and reliable, more on that inside.

Shooting the Shockwave

If you want to see a smile plastered on my face hand me one of these guns and take me to the range. I always enjoy shooting them. The fierce recoil is part of the fun to me.

Some people ride dirtbikes, some people race cars and ride bulls, and I shoot small 12 gauges without stocks. The technique and challenge in controlling one makes me happy. When I see buckshot hitting exactly where I want it to with one of these guns I get downright giddy.

So yes, I like shooting the Shockwave 590M, but looking objectively at the platform I can tell you a few things you need to know.

Shockwave 590M (3)

First, this gun is not for everyone. It’s hard to control, especially when you move beyond birdshot and into buckshot. Mossberg’s manual advises you shoot from the hip, but that seems unsafe to me in terms of knowing what you are going to hit.

That brings me to my second point, aiming the gun and recoil. You can, with proper technique, aim this gun with a reasonable degree of effectiveness. The method I use is pushing forward with the nonfiring hand and pulling rearward with the firing hand.

This method creates tension and helps stabilize the firearm throughout its recoil impulse. While holding it, you aim it like a stocked shotgun. If you are doing it right, you won’t punch yourself in the face.

After you shoot you relax the push and pull, and then rack the gun and go right back into the push-pull mode. This tension and muscle control can grow fatiguing, and after ten rounds in a rather rapid manner, you’ll feel it.

Shockwave 590M (12)

It’s almost a workout after a bit, but a fun one. The weight of the gun without a stock, the extra weight of 10 rounds of 12 gauge, and the recoil will give you a solid upper body workout.

Lastly, firing this gun isn’t painful. (Unless you punch yourself in the face.) As someone who’s handled shotguns with pistol grips, I can say they are rarely pleasant. A 90-degree pistol grip is not comfortable and causes pain, and the Shockwave Raptor grip is a pain-free pistol grip.


The Shockwave 590M features some impressive ergonomics. I was worried that the magazine would make it feel unwieldy, or I guess more cumbersome, but this wasn’t the case. The magazine is positioned where you would typically load shells.

That puts it dead center of the gun. The magazine placement aids in balancing the weapon, even with a full metal it doesn’t pull you one way or the other. The Shockwave Raptor grip makes it very easy to reach the Mossberg’s Tang safety and slide it with ease.

The Raptor grip is comfortable and fills the hand and the pump is a corn cob forend with a strap over it. This loop is a safety device that keeps your hand from getting in front of the barrel and potentially preventing the loss of a few digits.

Shockwave 590M (8)

The idea is excellent, but the execution needs refinement. The strap is held in place by two screws, and those screws are on the inside of the loop. Recoil can cause these screws to come back and bite your hand if you hold it too close to the front of the pump.

It can and will break the skin so be cautious how you hold it. The magazine release is perfect. It’s ambidextrous, and all you have to do is push it right or left, and you can remove the magazine.

The magazine rocks in slightly like an AK magazine, but not as dramatically. The near useless tube houses a catch for the forward lip of the magazine. Its pinned in place through the tube.

I did notice it takes more force to work the action and the pump is way less smooth than a standard Mossberg. It’s rough, it’s gritty, and it takes real power to throw it forward. This is because the pump rolls over the magazine, which creates tension due to the upward pressure.

I also noticed the trigger is much stiffer than a standard Mossberg 590. I’m not sure how and if this is an effect of the magazine or not, but its worth noting.


I mean – it is a shotgun with a 15-inch barrel and just a pistol grip, so how accurate is it? We can’t precisely measure groups but it’ll put buckshot where you need it to if you do your part.

Accuracy is subjective in general with a PGO 12 gauge it’s super personal. It’s also not a factor I’d consider when buying a gun like this.


Here is the real key to success. A pump-action shotgun is a simple thing, a simple idea that works and works well. Does adding a magazine risk that?

Good question, and so far, nope. A few hundred rounds of birdshot and a couple dozen buckshot proved the magazine worked and never stalled or failed to feed. The faster and harder you pumped the gun the easier it will cycle.

Shockwave 590M

One, and the only, magazine issue I had was loading it. Holy Crap is this spring strong. Past round 8 and I was shoving shells with one hand to load the other two.

The other issue is the rim of the shell catching the brass collar and refusing to go all the way back. This requires some finagling to make work, but you learn to load it smoothly after a few tries.

Who is this Thing For?

Do you like fun? Dumb, freedom style fun? If yes then this gun is for you.

If you are super serious, and say, “Train like you fight,” more than once a day then this thing likely isn’t for you.

It’s a fun gun, and it may have some minimal self-defense roles, those roles aren’t going to apply to most everyday joes. If you want a home defense shotgun – choose the Mossberg 590, or even the magazine-fed 590M over the Shockwave.

If you want a fun gun, this is the route to go. It’s a little ridiculous, but it puts a smile on your face.

Can We Make it Better?

With all this in mind, what can we do to make it better? You could also do the Form 4 route, pay 200 dollars, fill out some paperwork and wait six months to have an SBS with a 15-inch barrel and a proper stock.

Alternatively, you can add a stabilizing brace to the system. Yes this is legal to do, and plenty of people have done, it including me.

I added an Ergo adapter that allows me to add an AR-15 buffer tube and an AR pistol grip. I added an Ergo grip and then went with the Gear Head Works V2 brace.

Shockwave 590M (4)

The V2 is an adjustable brace that can slide up and down on a proprietary buffer tube. The use of a proprietary buffer tube means there is no risk of “Constructive Possession” when you own this set-up and a lose AR 15 stock.

With the stabilizing brace, the gun is much more manageable and easier to use. It makes more sense as a defensive firearm and is a lot easier to shoot in this configuration.

I only just got the Shockwave 590M, but I’ve got a Magpul pump on order too. My other Mossberg wears one, and I love it for attaching accessories. The gun is also drilled and tapped for a scope mount, which makes it a natural fit for a red dot optic.

By the Numbers

Reliability 5/5

It’s a pump-action shotgun they added a little complexity too. However, it still works, without a single hiccup. The magazine feeds reliably, the gun pumps like a champ, and it just runs and runs.

Accuracy ?/5

It’s a PGO shotgun, what kind of accuracy can we expect? I mean I can put buckshot where it needs to be, and that’s good enough for me. I mean its a 12 gauge, so….

Ergonomics 3/5  

The only reason it gets a 3 out of 5 is that handling a PGO shotgun is difficult. In general, the weapon’s weight, sight, and controls are all great. The controls work well and are easy to reach.

Looks 3/5

I’m torn here. I love the looks of a shotgun with a short barrel and bird’s head grip… but the magazine makes it seem odd.

It looks much better and more natural with the brace than the alternative, but there it is.

Customization 5/5

Its a Mossberg 590 and at the end of the day you can swap and change parts at random and as often as you want. The 590 and 500 by extension is one of the most popular shotguns in the world, and there are tons of parts for it.

Overall 4/5


The original Shockwave looks dainty compared to the 590M Shockwave. With all that extra beefiness, though, you get a great deal more capacity. The reliability and customization are stellar and it’ll hit what you point it at. It might not be the prettiest or most ergonomic “shotgun,” but it does a great job.

If you want a workout, you’ll get one from the Mossberg 590M Shockwave. Fire 50 rounds through it, and you’ll feel it. Your arms and shoulders will be tired from the tension method, and your fingers will be exhausted from loading the gun over and over.

Shockwave 590M (7)

It’s so much fun though, and so utterly ridiculous. I love it. It’s a fun gun, and a weapon I enjoy. It’s not for everyone and its pricey for a fun gun, but still, it’s fun.

A lot of folks will talk about how worthless it is, and to them, I say, “Lighten up Francis.”

Best New Range Toy
at GrabAGun

Prices accurate at time of writing

Prices accurate at time of writing

Available Coupons

So, what do you folks think? Is it for you?  For more awesome shotgun and Shockwave content, check these out: Mossberg ShockwaveRemington Tac-14.

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5 Leave a Reply

  • Commenter Avatar
    Charles Desalvo

    BEWARE of Mossberg! The unit I got jammed with the snap cap/practice rounds, brand new, right out of the box. Same thing at the range with good ammo. Mossberg wanted me to pay for shipping back until I complained (45 minutes wasted on the phone) and now they say 6-8 weeks to fix a gun that as defective out of the box. Their customer service, while nice, doesn't "listen" to the customer and forces their processes without consideration for the customer. Beware, dealing with them is not like dealing with so many customer concentric companies today! Several phone calls, and several emails and still no gun. Customer service intercepted my email to the CEO and wont allow my communications up!

    November 28, 2019 11:38 am
  • Commenter Avatar
    Ray Poteet

    Most gun reviews are bad at best, turning into a battle of opinions, yours was not. Thanks for seeing this one from all around! Good job.

    December 27, 2018 10:42 am
  • Commenter Avatar

    'Back in the day' an uncle of mine had one of the Sentinel-12 'street sweeper' shotguns. We used to love wasting old shells and crappy reloads through that thing. Talk about a blast.

    Absolutely useless at any sort of normal bird-shooting range of course, but some people tried. There was a dead tree with only the standing trunk left, about 4ft dia and 10ft tall, that was eventually cut in half by repeated assaults from the Sentinel. I don't think I ever saw anyone shoot less than 8-10 rounds once they got going.

    The only thing I remember actually killing with it was feral cats (that's a WHOLE other story) and raccoons. At the time I was living on my uncle's property as a caretaker, he was living about 3hrs away. We had ~4500 acres to play with and did white tail deer leases in the winter. My friends and I took full advantage of the man-made pond about 40yds from the house every evening during dove season.

    The ancient house had lots of space underneath for critters to crawl around. One very cold winter night after a party a coupe of coons got in a full on brawl right under the fireplace, I guess it was the warm spot, lol. Woke everyone inside the house. A couple guys went outside with flashlights and tried to scare them off but the coons, already bloodied and now hot-blooded as hell came after them. Someone suggested shooting but no one really thought shooting under an old house was very smart. So I broke out the street sweeper and started loading the drum and winding the spring. I went to one side of the house, fired a shot towards the back yard, and started hauling ass towards the front yard. I came in behind those two coons and mowed them down with every round left in the gun. And when I got back inside the party had somehow restarted!

    Yeah, I remember those days with 4500 acres and the neighbors were 4mi away... Those were good times.

    October 22, 2018 3:28 pm
  • Commenter Avatar

    Great review, would like to shoot but dont think I would buy one as my safe is full and it would only be a novelty for me. Thanks for the info

    October 13, 2018 5:07 am
    • Commenter Avatar
      Eric Hung

      You're so welcome!

      October 14, 2018 6:00 pm
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