NEW: NON-NFA Shockwave now 20 Gauge— Mossberg’s Ultimate Truck Gun

One of the hottest firearms introductions of 2017, announced at the SHOT Show in Las Vegas, was undoubtedly the Mossberg 590 Shockwave, which was originally chambered in 12 gauge. Right on its heels came Remington with the 870 Tac-14, another wildly popular defense shotgun, and yet another confirmation of the worth of a compact shotgun that can be had without climbing a Mount Everest of bureaucratic red tape.

Mossberg Brings the Heat

The genius behind the Shockwave is that it features a 14-inch barrel but avoids NFA classification since it is produced from the factory with a pistol grip and is above 26 inches in overall length. Same great performance from the 590 build, now in a compact package that’s ideally suited for personal defense situations.


  • Gauge: 20
  • Action: Pump
  • Capacity: 6
  • Barrel: Heavy-walled
  • Barrel Length: 14 in.
  • Sight: Brass front bead
  • Choke: Cylinder Bore
  • Grip: Shockwave Technologies Raptor
  • Forend: Cob-style, synthetic strap
  • Weight: 4.9 lbs.
  • Length: 26.37 in.
  • MSRP: $455

In the fall of 2017, Mossberg extended the Shockwave to include a 20-gauge variant. In design, it is identical, with the obvious exception of shell selection, and features the Shockwave Technologies Raptor grip. Overall length is 26.37 inches, with a 14-inch barrel and 5¼-inch pistol grip. The cylinder bore accommodates shells in 2¾- and 3-inch loads, with an overall capacity of six shells. As a 590, the shotgun features a thumb safety with red indicator and a slide lock release lever at the rear of the trigger guard.

Avoiding the NFA

So how exactly does the Shockwave avoid inclusion in the NFA required listing — which also includes short-barreled rifles (SBRs) and machine guns — with a $200 tax stamp to accompany it? According to the BATFE, an NFA-listed shotgun would have either a barrel less than 18 inches in length, or an overall length less than 26 inches. But since the Shockwave features a pistol grip rather than a buttstock from the factory, it is classified as a pistol grip only (PGO) firearm, and as such it can have a barrel shorter than 18 inches as long as the overall length is greater than 26 inches — hence the overall length of 26.37 inches. Buying age is thus 21 years of age, and state laws still apply.

Recoil & Distance Matter

One of the main questions I had entering testing was how the recoil of the 20 gauge would compare with the 12-gauge model, which I have reviewed previously, especially when paired with Aguila’s Minishell and the OpSol Mini-clip adapter. While the standard 12-guage 00 buckshot loads were less than pleasant to shoot, the Minishell greatly reduced recoil while maintaining lethal effectiveness. Recoil matters with the Shockwave, primarily because you’re not shouldering the shotgun, and hence your hands rather than your body are absorbing the majority of recoil. Since there’s obviously far less mass in your hands than your body to absorb recoil, it is felt all the more.  

From 7 yards, the 20-gauge Shockwave delivers a tight, lethal cluster of buckshot from Federal Premium’s 2¾ loads that carry a ton of stopping power.

I tested the Shockwave with Federal Premium’s Personal Defense 2¾-inch No. 4 buckshot loads. Copper-plated and offering acceptable penetration inside the home, the No. 4 buck sends 24 pellets at roughly 1,100 fps. As compared to 00 buck, No. 4 buckshot will penetrate roughly half as far, somewhere in the 7- to 9-inch range, but will deliver more pellets on target (of lesser weight). No. 4 is more ideal for inside the home, as compared to 00, because many 00 buckshot loads will penetrate well beyond the target, creating a real risk of injuring or killing other people in your home.

The Spread

One thing to keep in mind is the length of barrel on the Shockwave — 14 inches — and how the shorter length affects pellet spread. On a full-length shotgun (20 inches or greater), 00 buckshot has a maximum range of close to 20 yards — where all the pellets are still on target — and beyond 30 yards something like half of your pellets are off the target. With a shorter barrel, loads will typically spread out more quickly. Keep in mind, the other major factor is load selection. With the Shockwave, 15-20 yards is about your maximum effective range, depending on load. All that to say, it’s a short-range defensive weapon.

At 12 yards, the buckshot pattern begins to open, thus “spreading the love” with the 24 pellets on target and creating massive trauma. The combination of Federal Premium buckshot loads and the 590 Shockwave make for a devastating personal defense weapon

In terms of recoil, what I found was that the 20-gauge No. 4 buckshot loads still produce enough recoil to make the shotgun less than comfortable to shoot, especially on the forend grip. At the back of the synthetic strap there are two rivets where the strap attaches to the pump stock, and this bites into the hand during recoil. Gloves improve things, as does the adrenaline that would be coursing through your veins in a defensive shooting situation.

Selecting the Gauge

Range testing was conducted with Federal Premium’s Personal Defense 20-gauge loads buckshot loads.

While it’s nice to have a 20-gauge option, one thing to consider is the selection and availability of 20-gauge buckshot loads in your area. Federal Premium, Winchester, and Remington all produce them, but at least in my neck of the woods it’s far easier to find any defensive load in 12 gauge (except for the Minishell), especially if you’re looking on the shelves of your local hardware store. Still, a brief web search will get you everything you need, and there are some fantastic defensive loads out there for the venerable 20.

Shoulder or Hip?

One common myth is that a compact shotgun like the Shockwave can’t be raised to eye level to shoot, lest the recoil punch you in the face. Well, folks, there’s a reason it’s got a front bead sight on it. While hip shooting is remarkably effective at close range and with a few practice shots, the Shockwave can be easily fired at eye level without giving you a black eye. This is true for both the 12- and 20-gauge models. One thing I’ve noticed is that without a buttstock and proper cheek weld, I tend to shoot high. With a little practice, it’s easy to make the adjustment. 

The 590 Shockwave features a brass bead front sight and has a total capacity of six shells.

Range Tested, Gun Writer Approved

I tested the Shockwave using Federal Premium Personal Defense No. 4 buckshot loads at 7 and 12 yards, and in both instances, it was highly effective. At 7 yards there was a tight cluster of trauma, with 24 pellets entering the vital zone. At 12 yards all pellets were within an 18-inch spread, giving me confidence that it would easily be a devastating 15-yard defensive shotgun, perfect for the truck or home.

The 590 design has stood the test of time, and the Raptor grip works well to reduce size and recoil. In my opinion, this might be one of the most versatile personal defense weapons on the market today, and it doesn’t require a tax stamp. With No. 4 buck, the Shockwave is capable of delivering 24 pellets all at once on target, making it a highly effective way to defend your home, family, or self. It’s small enough to stash in a vehicle or closet, and with proper training is a fairly easy platform to learn how to shoot well.  
For more information about the Mossberg Shockwave, click here.

To purchase, a Mossberg Shockwave on GunsAmerica, click here.

{ 11 comments… add one }
  • Richar January 23, 2018, 6:30 am

    Was wondering if these will shoot the mini shot shells the ones smaller than2 3/4”

    • Wayne Nelson January 23, 2018, 11:32 am

      I’m told that, to date, the mini-shells are only being produced in 12 gauge and I’ve only seen the required adaptor in 12 gauge, as well.

  • Tommy Barrios January 22, 2018, 8:57 pm
  • Doug January 22, 2018, 5:36 pm

    I almost bought one of these at a gun show here in Ohio. But I got a weird vibe from the way the dealer answered questions about how legal the firearm was. So I held off and checked on-line when I got home. Glad I did. While it turns out that while the Shockwave is legal on the federal level, Ohio has a law on the books that prohibits ownership of shotguns with a barrel less than 18″. Under Ohio law the Shockwave is a shotgun no matter how the BATF lists the firearm.

    So while I think that it would be excellent for home defense in a condo, I’d be looking at a felony bust under state law for just owning the thing, let alone using it in a defense situation. If Ohio law ever changes, I’ll be first in line to buy one. But it would be felony stupid for an Ohio resident to buy one at this time. I understand that there are a couple of other states with similar laws. Too bad, it’s a really neat and well executed firearm.

  • Tim January 22, 2018, 3:06 pm

    I’ve had one for several months now; bought the 20 gauge at a local gun show for under $400.

    I’ll disagree with your comment regarding recoil; compared to other shotguns I’ve fired the recoil of my Shockwave seems less then and more manageable then other guns. After watching a Clint Smith review of him shooting the Mossberg 12 Gauge Shockwave I tried the hold he used – and was impressed. What Mr. Smith did was shoulder the gun (without putting it on his shoulder) as if it had a stock! At first it looked awkward but recoil was mild.

    Loading #4 Buckshot I also found the it grouped high; but between 10 and 15 yards there were still enough pellets on target to ruin a bad guy’s day (or night).

    I opted for the 20 gauge because I think it would be easier for my (normally) non-shooting wife to handle. Since the Shockwave has taken a position in the bedroom as a primary defense gun I feel its important for her to know how to use it and not be afraid of the recoil.

    All in all I am quite pleased with my purchase!

  • Wayne Nelson January 22, 2018, 2:58 pm

    Forgot to mention in my previous comment that my buddy has the new 20 gauge version – set up just like mine with a sling & Center Mass laser. Shooting them side-by-side, we could barely tell the difference in recoil or performance. Both shoot tighter patterns than we expected from such a short barrel and are “a hoot to shoot.”

  • Dave January 22, 2018, 12:17 pm

    Would like to know if and when Aguila is coming out with a 20 gauge minishell. I think that would be the ticket with this Shockwave.

  • Mark G January 22, 2018, 11:52 am

    I’m loving this, but am concerned that my wife might have problems with the recoil. She’s of small frame, and confidence with a weapon in defense situations is paramount.

    • Art Murray January 22, 2018, 9:53 pm

      Yer lyin’! Your wife is big and fat just like the rest of our wives!

  • Wayne Nelson January 22, 2018, 11:34 am

    I absolutely love my Shockwave 12, but the thing that makes it TWICE as great is the addition of a rail atop the receiver (gun comes already drilled & tapped) and a CENTER MASS laser array by Laserlyte. This tiny laser throws a concentric pattern of red laser dots that enlarges as distance to the target increases – just like the shot spread. With the laser activated and Raptor pistol grip firmly against my side above my hip, accurate shots are amazingly easy and recoil is minimal.
    I also use a lightweight sling (gun already comes with swivels) that I run behind my left elbow (shooting right-handed) and across my body to the rear swivel. Rock solid. Negligible recoil. Accurate hits on target. Amazing setup for defense or just plain FUN.
    The laser can be hard to see in bright sunlight at distance, but I’ve never had so much fun with a “12 gauge, pump action firearm.” (Not a shotgun)
    Seriously, I realize these reviews are for the gun the way it comes, but the way it comes sets it up to easily become something even greater.

    • ejharb February 4, 2018, 11:11 pm

      Might want to look into green lasers for daylight use.for some odd reason they’re more visable

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