Ok well technically one is a shotgun and the other is simply a firearm. But they both shoot shotgun shells. Both are fun to shoot but I have to give a bit of a nod to the KSG. The bullpup configuration keeps the OAL short. So short it almost feels like it should be NFA but it isn’t. Top that off with an impressive capacity. The downside is reloading the KSG and for some, the ejected shells hit them in the wrist. The Mossberg Shockwave is also a lot of fun but with a standard capacity of only 5+1 rounds, it loses to the KSG. Neither one comes threaded for chokes, but the KSG does have an adapter you can buy. You could easily send the Mossberg barrel out to be threaded by a competent gun smith. The KSG obviously comes standard with a top rail and bottom rail. You could swap out the ribbed foregrip for a Magpul handguard and add rails to the Mossberg. The top of the Shockwave receiver is drilled and tapped if you felt like adding an optic.

Which one would you prefer to use?





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  • Vhyrus

    The shockwave weighs about half as much as the KSG and you can holster it. That’s one hell of a good handgun.

    • JoelC

      *Firearm

      • Vhyrus

        Tomaytoe tomahtoe

        • Cymond

          Potato, potato.

          Who the heck says “potahtoe”?

    • Roguewriter

      On the other hand, consider that the full length version of the KSG, the KSG-25 will hold 40+1 Aguila mini shells. That’s one hell of a shotgun.

      • Vhyrus

        It’s almost like they are completely different firearms designed for completely different purposes, despite their shared mechanisms and ammunition.

        • USMC_grunt2009-2013

          I know right?!?!?

        • Roguewriter

          Captain Obvious! I didn’t recognize you with this name! lol

          • Vhyrus

            Actually I am Captain Obvious’s arch nemesis, General Sarcasm.

    • Calavera
    • 1LT Homer

      *For those who were curious*
      KSG -6.9lbs (8.5 loaded)
      870 Shockwave- 5.6lbs
      Mossberg 590 Shockwave- at 5.25lbs.

  • Code3Patriot

    The Magpul MOE M-LOK fore end for the Mossberg 590 does not fit the Shockwave. The mag tube diameters are a different size. Magpul’s product page for the fore end confirms that it does not fit.

    • El Duderino

      It doesn’t fit, but there are guys who have modified them to do so. Dremel and some time, that’s all you really need.

  • Dr. Longfellow Buchenrad

    Ive never shot a KSG, but I am a big fan of shouldering my shotguns so that pretty much settles it for me.

    • Xtorin O’hern

      sigbrace+ar stock adapter to the shockwave

      • Mmmtacos

        That’s a sticky wicket. Generally the ATF considers a Sig Brace an accessory. Accessories according the the ATF do not factor as part of the length of a firearm, hence why a muzzle device must be pinned to a barrel to give the barrel an OAL of 16″– otherwise it’s an SBR.

        Then again, the bird’s head grip of that Mossberg isn’t permanently attached either.

        I believe that proposition of yours would be best backed up with a letter to the ATF. Something tells me it has probably already been tried anyway, otherwise it would be on the market already. After all, the Mossberg and Remington factory offerings aren’t exactly new kids on the block: someone had been making 870s in this configuration for YEARS. It’s only now that the manufacturers realized it was an opportunity they were missing out on.

        • Xtorin O’hern

          my view on this is that if Black aces can get away with a non NFA 8 inch barreled 12 gauge pump “firearm” then then the ATF can shove it if they have a problem with the same thing in a longer configuration.

          • Mmmtacos

            Just a friendly piece of advice: the ATF doesn’t really care about your view.

            My point I was trying to make is that the Shockwave, and similar shotguns, bypass NFA laws because they were configured originally without a stock but maintain an OAL of 26″. That’s why they use the grip they do– because it protrudes out far enough to get them 26″ from ass to muzzle.

            An AR stock adapter that probably accommodates an AR grip as well probably wouldn’t meet the 26″ OAL since the brace wouldn’t factor in as part of that OAL.

            But hey, it’s your choice, let me know how it goes.

          • Xtorin O’hern

            the attachment of a pistol brace requires the attachment of a pistol tube which counts towards the overall length of the firearm, i can assure you that pistol tube is longer than the birdshead grip put on the shockwave

      • Gary Kirk

        You’d have to leave off the pistol grip..

  • Madison J Coleman

    You forgot to mention the Kel-Tec’s have piss poor build qualities and are 10x more likely to fail than Mossberg.

    • SP mclaughlin

      I’m no expert but they say that’s only true for the first batch of a given KT firearm. The post-first generation KSGs work fine.

  • Zundfolge

    I still contend that pistol grip only shotguns are silly … I also think most Keltec products are silly but in this case I’d take the KSG over the Shockwave under pretty much any circumstances.

    • Philip G Cathell

      That’s not a pistol grip, it’s a bird’s head grip. Feels better vs recoil

      • Zundfolge

        meh … the bird’s head grip is 98% as silly as a regular pistol grip.

  • Anonymoose

    Put an optic on it? I think a light and laser would be more useful.

    • El Duderino

      C’mon man. That Shockwave is just begging for a Nightforce 5-22x scope. Right?

  • Edeco

    I’d rather the Kel Tec. Weight could be good or bad, long story. There’s some specialized algebra for expressing and solving these things. Long story short the added weight of the Kel Tec is multitasking; first providing a shoulder stock and more shotgun bullet capacity, second soaking recoil. That tells me the Kel Tec is cooler.

    • Flounder

      Look up the weights online. The KSG is a few OZ lighter (at 7lbs and idk how many OZ) than a standard 500 (7.5 lbs -ish, so like 8 OZ more). So these are probably 1-2 lbs away from each other. fully loaded the KSG weighs significantly more.

      It threw me for a loop when i realized the KSG’s weight. Figured I would share.

  • Mergatroid

    Quit posting stupid articles and pictures….

  • Raptor Fred
  • Major Tom

    I have eyes on the KSG-25 when it comes out so the Shockwave is a complete no go.

  • lucusloc

    I would take a rifle, unless I was out fowling, then I would take a standard shotty.

    Both of the listed guns fall either into the “fun” or “self defense” realms.

    For fun there is no accounting for taste, but I don’t shoot shotguns for fun.

    For self defense, a good intermediate rifle with modern ammo outperforms a shotty in all but single cartridge power. I retired my self defense shotty years ago in favor of a good rifle with good ammo. Higher capacity, easier reloads, lighter recoil and faster follow up shots with less over penetration? Yes please. I know some simply find it hard to give up the shear intimidation that a good shotty has, and I cannot really blame them, but really rifles are where the home defense game is at.

    • Gary Kirk

      Welp.. If you need that intimidating noise factor, you could always answer that bump in the night with a rack of the bolt on a Barrett.. 😉

      • lucusloc

        apparently my reply got eaten by moderation. Attempt two, with minor changes (to avoid the autobots):

        Glaser Safety Slugs typically have some pretty terrible terminal
        performance, but I bet out of a .50BMG “terrible terminal performance (for a .50BMG)” would still be “Holy $^!&! Where did his chest go!?”. Someone needs to do a drywall pen test on that stat. We could usher in the age of the .50BMG as the choice of the truly discerning home defense firearm connoisseur.

        Plus if you miss everyone still dies due to blood loss out the ears!

        • Gary Kirk

          WHHHAAATT??

    • USMC_grunt2009-2013

      Rifles are highly recommended for home defense if you want to take out the intruder and that pesky neighbor who never trims his hedges.

      • lucusloc

        Modern expanding bullets from an intermediate power cartridge like .223 penetrates building materials less than 00 or 000 buck out of a shotgun, while still achieving the FBI recommended minimum penetration of 14 inches in gel. This means the rifle is *safer* than the shotty for your neighbor (with proper bullet selection of course).

        • USMC_grunt2009-2013

          M855 green tips and many other rifle rounds will go through drywall easily. Who said anything about 00 buck, #4 buckshot is where it’s at for home defense.

          • lucusloc

            Civilians have absolutely no reason to stick to military conventions. If you are using FMJ for self defense you are doing it wrong. Use a modern expanding bullet.

            #4 buck is a good choice, but I would definitely check out the gel tests for each individual loading, as results can fluctuate wildly. I have seen gel test results anywhere from 8 to 19 inches over the years.

            And of course no shotshell loading will change the platform benefits you get from using a mag fed rifle.

            I’ll stick to my 60gr VMAX with 30 on tap, in a lighter package, with much more manageable handling.

          • USMC_grunt2009-2013

            Fair point amigo, fair point. The reason I bring this up is because I know some people who aren’t really firearms enthusiasts, but have some old guns, an old 20 gauge and a .30-06 deer rifle, and asked my advice on which to use for home defense, knowing that I like guns and shooting. They didn’t want to buy an AR or any other gun, so I told ’em go with the 20 gauge and load it with #4 buck, for obvious reasons.

          • lucusloc

            Yeah, you work with what you have, and the 20 is a much better choice than the 30-06. But we also have to consider the people who are either into the sport, or who want to get into the sport. When they ask what should be the first home defense firearm they get (assuming we are not talking about a pistol), I am pretty much always going to recommend an AR-15 of some kind, unless there is a really good reason not to. That platform just has so many advantages that, all things considered, it will win out over just about any other modern firearm for sport and defensive uses.

            Long gone are the days where a shotty would have made it to the list for consideration. Now a shotty is only considered if there are other goals, such as fowling/clay shooting, competitions shooting or just general recreation. My “working” shotty now only sees the light of day for 3gun, nothing else.

            Do I still recommend a good shotty as part of a well rounded collection? You bet I do. Would I recommend it as part of a comprehensive defensive load out? Only if you are into hard core prepping. For everyone else a decent rifle and a pistol will more than cover you for self defense needs short of scavenging ammo at TEOTWAWKI. If you still want to use a shotty I cannot say you are wrong, they are still perfectly viable in that role, but I will never recommend them to new people wanting to prepare for self defense, and I would advise even seasoned shooters to reevaluate their choices, and reconsider the intermediate power rifle again.

          • USMC_grunt2009-2013

            All true, good points. When you recommend an AR for home defense, particularly if this person is just getting into firearms and maybe doesn’t have a good grasp on ballistics and whatnot, make sure you reaaaaaally emphasize using fragmenting ammo, like you said. I’ve ran into a few people who have their home defense AR loaded with green tips or M193 or bimetal steel cased Tula ammo, because “it’s much cheaper, this is what the military uses, etc.” who don’t understand how easy it is with this type of ammo to shoot through a wall or door or whatever and hit a bystander by accident. Gotta educate the inexperienced folk, it’s crazy what people will do out of ignorance.

          • lucusloc

            Oh yeah, educating them on differences in ammo is important no matter what system you choose. Just like you want to teach people not to use slugs or birdshot for home defense in a shotgun (or even mix lethal and less-lethal rounds in the same gun!), people need to be taught not to use FMJ or super light varmint rounds in a rifle.

            I still have discussions with the old codgers at the range who insist on using .45 ball ammo, because that is what pappy used. No, I still don’t want to be shot with it thankyouverymuch, but that does not mean it is as safe or effective as modern expanding ammo. The firearms industry is really slow to move (I feel I was late to the rifle-as-primary party, and I made the switch over a decade ago), but we really should be well past the stage where the grand old shotty is considered premier for home defense. It really should be consigned to the “fond memory bin” with the lever actions and muzzle loaders, with occasional service in specialty applications like bird hunting, door breaching or weird munitions deployment.

            Do us all a favor and stop telling newbies to get the weapons system with just about the most punishing recoil commonly available, and instead point them to something far easier and more fun to shoot (not directed at you specifically of course, but rather the community as a whole). Plus the platform will allow them to grow into the hobby in a much more incremental way, because they can buy accessories and even whole new uppers as they want to try new stuff, instead of having to invest in a completely new firearm. Only when they express interest in birding or clays (or perhaps the occasional hard core prepper) should they be directed to a shotty, and hopefully by that time they will have absorbed enough education to know more or less what they really want.

          • USMC_grunt2009-2013

            Well said, I like it.

            Hopefully the Internet will allow people to gain useful firearm knowledge easier. What worked best in 1980 isn’t best anymore, lol.

  • Texas-Roll-Over

    KSG MSRP: $990.00
    Mossberg MSRP: $455.00

    Different tools for different work.

  • James

    I RO’d a guy running a KSG this month in our 3Gn match.

    All I could think was how clunky and awkward it was. I’d definitely pass on one.

  • Mmmtacos

    Neither is practical, they’re just range toys.

    That being said, I’d take the Mossberg. That being said, I wish it were a Remington. That being said, I don’t like the Kel-Tec because I think it’s ugly. That being said, if Kel-Tec could get over their obsession of using raised squares for grip-texture I’d probably be more keen on them.

    • Gary Kirk

      All that having been said.. I’m right there with you on the Remington, as long as it about 20+ years old..

      • Joby

        10+ and you’re good. Freedom group bought them out in 2006 or 2007, I don’t remember which

    • Philip G Cathell

      There is a Remington one. Also, look at Scott’s gunsmithing in Maryland for their urban broom

    • USMC_grunt2009-2013

      Remington has gone downhill fast. Maybe an old Remington.

  • Gary Kirk

    Can I (usefully) hunt turkey, geese, or upland withering them?..

    There’s your answer.. As far as a shotgun goes for me..

    • Anonymoose

      You could put a long barrel on it and then add a stock, but you’d have to take the stock off before swapping barrels to the short one again.

    • AndyHasky

      I would totally take a ksg dove hunting, just have to plug one tube and limit the other to two shells.

    • BaconLovingInfidel

      You’ve got to sneak up really, really close.

  • Now if only Mossberg would make a 590a1 bullpup with one magazine tube, the KSG’s length, and absolutely zero Kel-Tec clamshell nonsense.

    PS – the 500 Bullpup of 80s fame doesn’t count.

  • alex archuleta

    I been thinking pretty hard about adding a grip, adapter and shockwave pistol stabilizer and taking off the Birdseye grip on my mossberg shockwave. Any thoughts?

    • As far as I know, you can’t. What Mossberg hangs their hats on is that the design is the way it is from the factory. Once you modify it, as far as I’ve been advised by legal opinion, you are back in SBS territory and may need a stamp.

      • Qoquaq En Transic

        Yup.

        If it came from the factory without ever having a stock, that’s one thing.

        But if it has EVER had a stock on it, even for 1 second, you then have an NFA item if you put a pistol grip (or a birdshead grip) on it.

        Stupid, but true.

        • alex archuleta

          Okay so even if the shockwave stabilizer isn’t considered a “stock” by the atf, and I still stayed over the 26in min. It’s still considered an nfa weapon if I put on the shockwave pistol stabilizer?

          • Qoquaq En Transic

            Honestly, I don’t know for sure. I wouldn’t think so, but this is a gray area where an “overzealous” ATF agent (if he knows how to play the game) perhaps could cause you problems.

            I’d say you could, but I’d hate to have to defend it in court.

            I’ll leave the answer to someone else who has better knowledge in this area – and since I”m not a lawyer.

          • alex archuleta

            So I called shockwave industries and told them I wanted to add the shockwave pistol stabilizer and kak tube w/ pistol grip to the mossberg shockwave that I bought.
            His words were,” yes you can do that, I’m not a lawyer but as far as I know that’s okay to do and you should be kosher. Plus I believe there are already a few options out there for something like what your asking.” (I believe he was talking about the black aces firearm, but he didn’t say)
            I just wanted to clear it up cause if I thought of it, then I’m sure someone else has too. Thank you guys for the advice 🙂

          • Qoquaq En Transic

            Thanks for the info.

          • BaconLovingInfidel

            No, you’re good to go.

        • alex archuleta

          So I called shockwave industries and told them I wanted to do.

          His words were,” yes you can do that, I’m not a lawyer but as far as I know that’s okay to do and you should be kosher. Plus I believe there are already a few options out there for something like what your asking.” (I believe he was talking about the black aces firearm, but he didn’t say)

          I just wanted to clear it up cause if I thought of it, then I’m sure someone else has too. Thank you guys for the advice 🙂 according to shockwave, their pistol stabilizer isn’t a stock.
          And if you read the letter to shockwave from the atf, when talking about the shockwave they use the term firearm, not pistol so, as long as the shotgun or “firearm” didn’t leave the factory with a stock on it, but instead left with the birds eye pistol grip, depending on where you live, (legal in my state) you can go from Birdseye to pistol stabilizer 🙂
          Cheers

      • alex archuleta

        Thanks for the advice gents ! I didn’t want to do anything that would get in in trouble. I thought that because it was over the 26in oal that I’d be safe.
        And the shockwave pistol stabilizer isn’t considered a “stock” and I was still going to be over the 26in minimum that I’d be okay with in the law.
        That was my reasoning. Thanks!

        • The reason it would be verboten under the NFA is that pistol braces are only legal for pistols, and the 590 Shockwave isn’t a pistol, it’s a “Firearm”.

          • That, and you have now made a shotgun under the 18″ barrel requirement.

        • The key here is that it’s barrel is 14″. They’re using the loopholes in the law to make a 14″ barrel firearm ‘legal’, but the minute it’s modified, you’ve now made a short-barreled shotgun by the letter of the NFA.

          • alex archuleta

            Hello, thanks for the advice:)
            So I called shockwave and the guy I spoke to said it’s kosher to do that 🙂

          • *Shrugs* I can only tell you what legal council told us. The ATF is fickle and vague enough that I wouldn’t put anything past them and how they interpret the NFA.

  • Flounder

    The KSG has external threads at the end of the barrel covered up by a nut. Which you only hint at.

  • gunsandrockets

    Yeah, KT QC is questionable. Yeah KT pricing is questionable. Yeah KT availability is spotty.

    All that said, I was surprised at how light and handy the KSG is. It feels better than it looks.

  • USMC_grunt2009-2013

    Coming up next: Which would you rather have, a .357 Ruger revolver or a .357 Marlin lever action?

    They shoot the same ammo, so no it’s not stupid to compare them!

    • Cymond

      If the revolver is as long as the rifle, them yes, the comparison is apt.

  • Anonymoose

    Maybe we could do something with .45 Raptor and Glaser Safety slugs meant for the .45LC…

    • lucusloc

      Does this give me an excuse to use a full battle rifle for home defense? Yest it does.

      Do I get the intimidation factor of a really big bore for the bad guy to stare down? Yest I do.

      Does it stand a reasonable chance of having acceptable terminal ballistics? I have no idea.

      Hold my beer, I have parts to order. . .

      • Anonymoose
        • lucusloc

          Yeah, but now were getting into the realm of “frangible ammo really does suck” (and not just “sucks for a cartridge that is already massive overkill, and should therefor still be perfectly fine”). I would need to see gel and barrier tests to really consider something like that.

          • Anonymoose

            What about the PDX1 .308?

          • lucusloc

            Um, have you seen the drywall tests for that? It may fragment, but each of those fragments still has enough energy to carry right on through a house. . .

          • iksnilol

            House clearing without even entering the house, bruh.

          • lucusloc

            This, and other advanced tactics like “full auto blind fire room clearing” and “Shoot first, ID second” brought to you by Gecko45 school for tactical tacticians; “We trained the LAPD!”

  • Palmier

    Obviously the one you can shoulder.

  • nate

    I think the correct answer is their both good, so buy both, then add a benelli M4 and a Mossberg 590A1

  • imachinegunstuff

    Just as a heads up you have to modify the Magpul pump a ton to get it to fit the Shockwave. Magpuls website even states the Magpul for end isn’t compatible with the Shockwave.

  • Mike Crumling

    The KSG suffers from at least one major design flaw. The screw that holds the mag selector in place can walk out as the selector is flipped back and forth. It also is undersized for it role. the threaded portion of the receiver is also to small to be drilled and tapped to a larger size. There is plenty of space for a larger screw and threaded portion, but the issue is that if and when this part fails, it renders the gun completely useless. I’m just saying there’s no way I’d pay that kinda price for a gun with a single 4-40 screw for an Achilles heel.

  • rexell1951

    New don’t necessarily mean better. I’ll stick with my old Mossberg 12 gauge, and my way older Browning Hi-Power (Belgian manufacture) for defense around the house. Both have proven reliability. Both are all metal, no plastic anywhere. Both work!

  • frank

    At this time of year wouldn’t you rather have a TORO then a Shockwave or a KSG? Just a thought.

  • Tom

    Without hearing protection, I’d go with the Shockwave with Aguila mini shells. That gives 10 rounds. If I can’t defend myself in my home with that, then I deserve to die!… Also, the sound pressure level is not as destructive to my ears as a rifle round. It also makes for a good club when empty.

    WIth hearing protection, I’d call in close air support!

    40 grain pills out of an AR work really well too. I’d just need to get ears and eyes on first. I may or may not have time for that.

    I may or may not even have time to be able to grab a weapon leaving me with only my hands, feet and other tactical body parts for my defense.

  • Jon OathKeeper Perkins III

    ill keep my KSG

  • Colonel K

    Yes, the Mossberg barrel can be choked, but only if you eliminate the bead, move it back 2″ from the muzzle, or braze a raised base for a new bead. I’ve done all three, but since the bead is largely cosmetic, I would recommend eliminating it if you want the muzzle threaded for removable chokes.

  • William D. Adams

    Who can fire the mini shells reliably?