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Mossberg bills their non-NFA, not-a-shotgun 590 Shockwave the modern-day six-shooter. It may not be quite as portable as a Single Action Army, but it looks like it would make a hell of a good trunk gun or home defense blaster. Now Mossy’s adding a 20 gauge version to go along with the original 12 gauge model. Here’s their press release:

Mossberg® Introduces 20-Gauge 590® Shockwave® Non-NFA Pump-Action

Shipping Now to Wholesalers

North Haven, CT – Following the unprecedented success of the 590 Shockwave 12-gauge pump-action firearm, Mossberg announces the release of a 20-gauge version of the 590 Shockwave. Featuring a 14-inch barrel, “birds head” pistol grip and an overall length of 26.4 inches, the 590 Shockwave does not fall under the purview of the National Firearms Act (NFA) and does not require additional paperwork or the payment of a tax stamp for transfers. Federal Law does require the purchaser of this firearm to be 21 years of age. And coinciding with the announcement of this new 590 Shockwave, Mossberg is pleased to announce that the 20-gauge versions are already in production and shipping to wholesalers.

Based on the 590 pump-action design, the 20-gauge version of the Shockwave required an engineering redesign as this is the first time that Mossberg has offered the 590 platform in a smaller gauge. In addition to a scaled-down receiver, the cob-styled, tactical forend was reduced in overall size. Weighing in at a mere 4.95 lbs, this compact 20-gauge firearm combines the field-proven design of Mossberg’s legendary pump-action platform with the innovative Raptor® pistol grip from Shockwave Technologies; strapped forend for safe, controlled handling; and 6-round capacity.

At the core of the 590 Shockwave is Mossberg’s field-proven design which includes non-binding twin action bars; positive steel-to-steel lock-up; an anti-jam elevator; dual extractors; and Mossberg’s universally-recognized, ambidextrous top-mounted safety. The lightweight receiver is constructed of anodized aluminum and is drilled and tapped for ease of adding an optic or accessories. The magazine tube features a convenient clean-out cap. This 20-gauge is 2 ¾ and 3-inch capable with 6-round total capacity and features a 14-inch, heavy-walled barrel with bead sight and matte blue finish. Rear and magazine cap sling swivel studs complete this compact package.

The “bird’s head”-shaped pistol grip from Shockwave Technologies provides this 590 with its distinctive name. The Shockwave Raptor grip features an enhanced textured finish, allowing for maximum control while minimizing felt recoil. The grip is constructed of durable, glass-filled polymer with non-reflective, black finish and overall length of 5.25 inches.

Only Mossberg, a leader in the firearms industry and the world’s largest pump-action shotgun manufacturer, can offer a MilSpec 3443-approved pump-action platform (the only shotgun manufacturer to pass these endurance, accuracy and quality tests) in a 14-inch barreled non-NFA firearm. Now available in 12 and 20-gauge versions! For more information on the 590 Shockwave and other compact 500®/590A1™ offerings, please visit

Mossberg 590 Shockwave Non-NFA Pump-Action Firearm Specifications:




























Non-NFA Pump-Action


20 ga

3 in




14.37 in Hvy-Walled

Matte Blue




Cylinder Bore


26.37 in

Shockwave Raptor Grip

Cob Forend with Strap

Black Synthetic


4.95 lbs



Shockwave® and Raptor® are registered trademarks of Shockwave Technologies/Ewer Enterprises LLC.

Disclaimer: Although the Mossberg 590 Shockwave is classified as a “firearm” under the Gun Control Act of 1968 (GCA), and is not subject to the provisions of the National Firearms Act (NFA), state and local laws may be more restrictive. Even though it is legal federally, the 590 Shockwave may be considered a “short-barreled” shotgun or “assault weapon” by certain state and local laws; and therefore illegal to possess. Please check with your local authorities concerning the legality of possessing a firearm of this configuration.

About O.F. Mossberg & Sons, Inc.

Founded in 1919, O.F. Mossberg & Sons, Inc. is the oldest family-owned firearms manufacturer in America, and is the largest pump-action shotgun manufacturer in the world. Leading the way with over 100 design and utility patents to its credit, and standing as the first ISO 9001 Certified long-gun manufacturer, Mossberg is considered to be one of the most innovative firearms manufacturers in U.S. History. For more information on commercial, special purpose, law enforcement and military shotguns, rifles and accessories, please visit their website at

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      • Well we would have that if it wasn’t for the inanity of the NFA.

        The stock makes it more deadlier-er I guess?

        I like the ingenuity of the entrepreneurs to flout just how ridiculous this all is, but seriously, wish we could get past this.

        Shall Not Be Infringed.

        • The original idea behind regulating Short Barrel Shotguns and chopped down stocks was they were easy to conceal under a trenchcoat or overcoat. Today we have the Shockwave and it is by far the most concealable shotgun ever made.

          The Shockwave and even the KSG has made the SBS portion of the NFA obsolete.

        • “Today we have the Shockwave and it is by far the most concealable shotgun ever made.”

          Nope. It’s ten inches longer than the Serbu Super Shorty, which is a $5 AOW.

      • Put a laser on it and then you can aim from the hip and don’t need a stock. Unfortunately, the Magpul M-LOK Mossberg 590 forend is incompatible with the 14″ Shockwave variants, so it’s not nearly as easy to add a laser as the Remington Tac-14. Maybe Magpul will come out with a compatible forend. In the mean time GG&G sells a modified version of the Magpul forend that fits/works.

        • Mossberg drills and taps some of their receivers- a picatinny rail mounted laser could work if you swapped the bits from this gun onto one of those receivers. Alternatively, a FLEX fore-end and mount could be swapped in- there’s one fore-end that comes with a rail.

        • Stereodude,

          I’m not sure- I know it’d be fine up here in Canada provided the OAL remained above 26 inches (which according to Mossberg, it is), but I can’t really comment on US regulations.

        • AFAIK, you can’t use a receiver that was formerly part of a shotgun (legal definition) or you would have illegally modified one into a SBS even though it’ll end up looking and functioning identical to the Shockwave. Unless you can get a receiver with those features that was never part of a shotgun (legal definition).

        • (and I thought Canadian laws were confusing!)
          In that case, is it legal to drill and tap the Shockwave’s receiver?

  1. I’ve said it before, I’ll say it again: there is a huge untapped market for lighter recoiling defensive shotties out there – Mossberg seems to get that.

    • Yeah, but you can’t tell me that a 20 gauge with 6 shells in it is better than the 12 gauge loaded with 10 Aguila Minishells.

      • I’m waiting for Remington to figure that out and start building short-action ‘firearms’ and their own version of the minishells to go with.

        sure, it’s a 12ga (or 20?) that can only cycle the minis, but it would be the ultimate one trick pony.

        ….market it as your daughter’s/mother’s best home defense.

  2. “…Mossberg announces the release of a 20-gauge version of the 590 Shockwave.”

    Hello! 😉

    Do they make those shorty mini-shells in 20 Ga.?

  3. I’m still concerned over the legality of this type of firearm. Yes, Mossberg has a letter saying it’s not a shotgun, SBS or AOW, but my concern is that these are distructive devices (which the letters don’t discuss). The NFA includes large bore firearms (over 1/2 inch bore) in the definition of destructive devices, “except a shotgun or shotgun shell which the Secretary finds is generally recognized as particularly suitable for sporting purposes.” The problem is that this is not a shotgun, so the exception doesn’t apply. Ergo, it’s a distructive device.

    For the most part this is not a big legal risk. The ATF could suddenly realize the oversight and demand you register, but they are not going to start locking people up out of the blue. Rather, my concern is state prosecutors using state law that often mirrors federal law on this issue to prosecute if the politics of the moment demanded it. You may get off on a manslaughter charge by establishing self defense, but not the destructive device one, and they usually have pretty steep penalties.

    • Any shotgun with a bore greater than .410 (which is less than 1/2″) might be designated a destructive device at any time by the Feds. The ATF has already done so twice. See the Street Sweeper and USAS-12 shotguns.

      As for the states, when they want to get rid of some shotguns, they have only to reclassify them as assault weapons. Many states have already done so.

      No government in or of the US can charge anyone with a crime for doing something that was legal at the time and then made illegal after the performance of the act charged. So there’s that.

      But your point is that the Shockwave is already a DD, since neither the ATF nor a particular state has not ruled otherwise.

      As to the former, the ATF ruled that the Shockwave is not a “firearm” for NFA purposes, but is for GCA purposes. So far, so good. If it isn’t an NFA firearm, it isn’t an NFA firearm.

      26 U.S. Code §5845(f) defines a destructive device as “any type of weapon by whatever name known which will . . . expel a projectile by the action of an explosive or other propellant, the barrel or barrels of which have a bore of more than one-half inch in diameter,” except for sporting arms.

      So the question is, since the Shockwave isn’t a “firearm” for NFA purposes, can it be a “weapon” for NFA purposes. Because if firearm = weapon in this context, the NFA doesn’t apply. In any way. Which is, I think, the correct interpretation.

      According to the NFA: “d) Shotgun. The term ‘shotgun’ means a weapon . . .” etc.

      So, once the ATF ruled that the Shockwave isn’t an NFA item, it would appear that the Shockwave out of the NFA entirely.

      The effect on state laws can only be guessed.

      I’m a (retired) lawyer, but I’m not your lawyer so act according to your own lights.

      • The ATF letter said a Shockwave was not an NFA firearm, and the NFA definition of a firearm includes distructive devices. This means that ATF’s opinion letter was simply wrong when it said otherwise, and the ATF could choose to correct itself at any time.

        As for the effect of the letter, an agency opinion letter is not technically “law”, and it’s opinion letter is not a “ruling” in any real sense (in fact, the ATF does make official rulings, which are binding, but the letter is not one). While courts will defer to agency opinion letters when interpreting ambiguous regulations, here there isn’t really any ambiguity. (Contrast with the meaning of “sporting purposes”, which is legally ambiguous). In a criminal trial the letter may give you an entrapment defense, but only to a federal charge. For a state level destructive device possession charge, the ATF letter probably wouldn’t help. You’re basically at the mercy of the state’s attorney.

        • It’s easy to be concerned about imaginary laws. We can assume they don’t need a law to jam you up.

          And they don’t.

        • The state and the Feds can jam you up any time they want. They don’t need an excuse, and if they don’t have one they’ll make one up.

          You’re always at the mercy of the state’s attorney. It may be hard to accept, but it’s true.

          Right now, you’re wondering what you can do to avoid trouble. I get that and don’t intend any criticism. You could potentially avoid any and all potential trouble, but I don’t think you’d want to live that way.

  4. Do they make the Shockwave in a marine version? Something like this would be perfect on the boat, but would like something that’d stand up to the elements a little better.

    • All you have to do for marine applications is keep a light oil film on the metal surfaces. Preventing metal corrosion isn’t exactly rocket science. (Apologies — I couldn’t help myself!)

      • Eh, not so much.

        A salt-water marine environ is *rough* on gunmetal.

        You had better be *meticulous* with your maintenance around saltwater.

        Yeah, Mossie would be doing a very righteous thing by making these like their ‘Mariner’.

        (I’d happily pay 150-200 more for that in *stainless*…)

  5. Not needed. The 12 gauge is surprisingly manageable. I thought it would be unpleasant to shoot but not at all. And if you really want something tame, try mini shells.

    • Do you know if the Shockwave will cycle mini-shells? I’ve heard that Aguila Minis often jam up pump shottys by tumbling as the elevator lifts them.

      • Someone makes an adapter ‘thingy’ that allows them to cycle in the Mossie.

        Is that ‘Shockwave’ even legal in Mass?

  6. Looks good. For close quarters self-defense, I’d go with the 20 gauge. You’re not losing anything you’ll miss in terms of lethality over the 12 gauge, but you would gain more control through less recoil.

    Still, if that’s your purpose, the Mossberg youth shotgun in .410 is probably the better bet. You get essentially the same firepower, but with even more control. So I’m not really sure what the target market is here.

    • I think the target market is people who want the Shockwave’s compactness (shortness) without the recoil of a 12 gauge shotgun. I think this is going to be a winner.

      • Only target market this thing serves is 7-11 hold up crews. Sorry, but the gun world does not need this thing. Lets get back to using shotguns on birds & clays.

        • Unfortunately for your opinion of what people “need” in the way of firearms their guns are guaranteed by the Second Amendment which is in the Bill of Rights – Bill of Rights, not bill of “needs”. I have no use for a sporting shotgun and don’t understand why anyone would want to shoot birds or clays. Perhaps everyone should take a hacksaw to their sporting clays o/u and cut the barrels down to eighteen inches so they would have a legitimate purpose for defensive use. Not such a good idea when someone else is deciding what you need, is it? You and i should be able to own whatever we have the money to buy. Your opinion of what I “need” has no influence on what I want or what I buy and use

    • I figured the target market was anyone who wants a shotgun in an (almost) handgun sized package. That youth .410 has two deficiencies, it’s still a longarm and it’s a .410.
      I won’t lie, I was seriously considering one before in a 12, and now I think a 20 would be more my style… what can I say? I just like 20s.

  7. I know that it’s probably useless, but it looks cool and cool is enough. I’d buy one if I could.

    And for a $5 AOW stamp, I’d also buy a Serbu Super Shorty.

      • Most importantly, the overall length. The Super Shorty is 16.5″ in OAL. The Shockwave is 26.5″, ten inches longer. Being over 26″, with all its other attributes, takes the Shockwave out of the NFA. The Serbu at 16.5″ is considered capable of being concealed and therefore is an AOW.

  8. Yep, sign me up. 20 gauge delivers 75% of the 12 gauge’s stopping power with a recoil reduction of nearly 50%. That’s a good trade off…especially with this type of shotgun.

  9. They still don’t offer the complete HD package for smaller shooters: 5+1 capacity 20 gauge, Super Bantam adjustable stock and extended forend, 18.5 inch cylinder bore barrel without the rib. Anyone in your family strong enough to shoulder it can shoot it well with very little practice. I built one like this for my younger sister and she loves it.

    If we ever manage to get rid of the NFA, I’ll probably put a 14″ barrel on it.

    • I just bought the youth model 500 in 20 bore for my wife. She’s only 5 foot tall. It’s a decent compromise.

      And in a real end of the world situation if bugging out was a must I’d be tempted to take it and my H&R single shot 20 as our long guns. Light, easy to carry. Easy to take down and conceal and both capable of taking every thing from moose to pigeons with the right loads.

  10. …the modern-day six-shooter. It may not be quite as portable as a Single Action Army…

    All in all, I’d rather have a Single Action Army.

  11. I’d be more into these Shockewaves if somebody would but a pistol grip and a Sig Brace on them. No, I still wouldn’t shoulder the Sig brace, but I would shoot it from the hip and butt the end of the brace up against my bicep and the recoil would go back into my hand and bicep. I just don’t trust that grip on them now.

    Also, there’s no point to the 20 gauge since Aguila makes 12 gauge Minishells that increase capacity and that company in Texas makes the tool that feeds and ejects them reliably.

  12. Lets see:

    The 20 gauge Shockwave is less than 5 ounces lighter, (4.8), than the Shockwave 12 gauge. Interesting.

    The standard 20 gauge #3B payload weighs 460 grains and advertsed velocity of 1175 fps. These are simple buffered buckshot loads.

    Readily avallable reduced recoil 12 gauge 8 pellet 00B load comes in at 400 grains at an advertised velocity of 1145 fps. These are usually buffered with a shotcup wad. Indeed, Federal even makes these 12 gauge loads with the tight patterning Flite Control wad.

    Bottom line with these readily available 2.75″ buckshot loads the 12 gauge Shockwave will recoil less than the 20 gauge version!

    The only real advantage of the 20 gauge shock wave then is a slightly smaller receiver and barrel diameter. Very interesting!


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