The SIG MPX: The King is dead, long live The King

In this episode of TFBTV provided as a counterpoint to Alex’s MP5 video, James and Army Ranger Jacque B. take an in-depth look at the short barrel rifle version of the brand new SIG MPX. The SIG MPX is SIG’s new pistol caliber subgun that shares many features with the AR15/M16 platform, including a rotating bolt and common controls. It is also convertible from 9mm to .357SIG to .40S&W. James compares it to the Heckler & Koch MP5 and goes over disassembly, the internals, the quick change barrels, and brings some sweet, semi-erotic, slow-mo MPX footage to TFBTV.

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The SIG MPX  The King is dead  long live The King   The Firearm Blog

Steve Johnson

Founder and Dictator-In-Chief of TFB. A passionate gun owner, a shooting enthusiast and totally tacti-uncool. Favorite first date location: any gun range. Steve can be contacted here.


  • Joshua

    “… …. and that’s all I have to say about that”
    seriously, could not hear Sgt. Jacque at the beginning

  • AR style charging system makes it inferior to the MP-5.

    • Yimmy

      I agree completely. In a semi auto pistol caliber carbine/pistol, it’s just ridiculous.

      • Even ridiculous in the original as well. Weak side charging is the only way to go in any shoulder weapon.

        • CavScout

          You must not be talking about an AR15… Idk about you, but I use my off-hand to grab only the left side the of the CH and latch to charge an AR. There’s no more whole hand over the gun with split fingers – charging. Most people stopped doing that years ago…

          • You can’t do that without breaking contact with the stock.

  • Emfourty Gasmask

    Way overpriced.

    • >’w'<

      You could pay $400~600 for a stock on ebay, not to hard….

      • JumpIf NotZero

        Difficulty isn’t the issue there.

    • USMC03Vet

      It’s SIG. It’s required by law to be overpriced.

      • James R.

        LOL FACT

  • Riot

    I don’t like it and I think the mp5 is still better.
    It has a bolt hold open as standard for an advantage – It also has stoner’s daft charging handle as a disadvantage which more than cancels it out. Weights similar too so it isn’t ahead there.
    And being like an AR15 is not an advantage – it’s just coddling those that want to live in a sheltered little world where everything seems the same and it needs to stop.

    • CommonSense23

      If you actually work with a gun, the charging handle in the rear is a awesome place.

      • JumpIf NotZero

        I like the AR handle on ARs. But on the much much smaller MP5, MPX, Evo, sized guns I really do prefer the MP5/Evo forward location.

        Under normal and moving use, since everything but the MP5 had bolt hold open, it’s really about all the same.

        For me it’s support thumb to release mag and strip away, grab new mag, insert and thumb to release slide (AR, Evo, MPX). The only time I touch the charging handle is malfunctions or admin load.

  • Stompy

    CZ scorpion FTW. Much more economical and cheaper mags too.

    • JumpIf NotZero

      I do absolutely love that the mags have been flawless and are $20 at retail and they’ve been in stock every time I’ve looked for them!

  • Kyle

    I like it but the price tag is stiff. Especially with that Scorpion EVO out there for a several hundred less. Everything I have read about the EVO raves about it and while I like AR commonality it isn’t worth that much extra money to me.

    • As the owner of a Scorpion Evo SBR, I can assure you that it is not nearly as good as the MPX.

      • Stompy

        True. I’ll pass on the MPX. More interested in the Sig MCX.

        • Gern Blanston

          the mcx is definitely sig carbine to have!

      • JumpIf NotZero

        As an owner of the Evo, an MPX Gen2, a fullsize and a K/RS size MP5…. I disagree entirely.

        The CZ is a beater MP5. It’s everything the UMP should have been.

        The SIG has potential, but they’re doing everything they can to screw it up. Gen3 MPX might be comparable.

        For the most part, the Evo makes an excellent compliment to the MP5. The Sig tries to replace it but does so with no track record at all.

        • You will like tomorrow’s video, which is a retort to James’ MPX video.

          • JumpIf NotZero

            Dude, spoiler alert!

          • mosinman

            i knew you wouldn’t pass up a chance to defend a HK gun 😉

        • Nicks87

          EVO SBR FTW!!!

      • Yimmy

        That may be but for half the price, I can’t see how the mpx is twice as good either.

      • Ian Thorne

        As someome who owns a scorpion SBR and shot the MPX SBR several times, I completely disagree. Especially if you are one of the chumps who already has an outdated and obsolete model.

        It tries so hard to be a 9mm AR, people should just get a 9mm AR. Cheaper more parts.

        • I would like to be on record as saying I dislike the Evo and am indifferent towards the MPX.

    • Reef Blastbody

      For what SIG wants for their quasi-AR 15 pistol caliber carbine, I’m opting to build a Quarter Circle 10 carbine in 10MM so I can share magazines with my Glock 20. The extra kinetic energy delivered from a 10″ barrel in 10MM vs the 5″ barrel on the Glock is icing on the cake.

      And I’ll be well under the price of an MPX even factoring in the $200 NFA stamp.

  • Everything I’ve shot has been good. I’ll be covering the SIG shoot on Monday.

    • JumpIf NotZero

      … You are a firearm blogger.

      Show me a review of a gun you didn’t write nice things about.

      • James R.

        Wrong blog, homie. This is a pretty straightforward publication. In recent memory, check Nate’s review of the UZI Pro.

        • JumpIf NotZero

          I’m talking about Phil White who has never see only shot a gun that he didn’t officially like.

          • James R.

            He’s the Associate Editor, he doesn’t have to shoot the crap guns. 🙂

      • Read like, most of mine.

        • Giolli Joker

          But you’re like ladies with shoes, you find defects to justify new purchases… 😛

  • Lance

    MP-5 is still way better and is more relighable.

  • Andrew

    Ok, now let’s talk about the fact that there are already 2 “gens” of the MPX (soon to be 3). Gen 2 mags aren’t backwards compatible with gen 1, so gen 1 owners are SOL when it comes to spare mags, unless they find some for sale on the secondary market. Gen 2 uppers won’t work with gen 1 either, so no caliber conversions or replacement barrels for the poor suckers who purchased an early gun. The charging handle is poorly designed and sloppier than a cheerleader on prom night. It flexes side to side and chews chunks of metal out of the receivers. This issue has yet to be fixed by Sig, although they continue to claim it has. Barrel nuts stripping out upper receivers and numerous other issues have been well documented again and again all over the Sig rifles forum on arfcom. Wouldn’t touch this gun with a 10 foot pole for the low price of $1500.

    • James R.

      Hate that I didn’t see this earlier so people have been reading this about the mags, CH, and uppers, thinking it to be fact.

      (1) How many “generations” of the MP5 have there been over five decades? Or any platform for that matter? SIG should be applauded for investing in its product instead of just pumping it into the market, hyping it up, and abandoning it on the tech side. They obviously take this carbine very seriously.
      (2) Mags are cross compatible between Gen1+2, they just recommend using the correct gen mag.
      (3) The Gen1 and Gen2 lowers are the same. SIG is offering Gen1 owners a free Gen2 upper upgrade when they buy a conversion kit. Honestly, I don’t know what’s “wrong” with the Gen1 that there needs to be a Gen2, but, again, see #1.
      (4) I’ve charged the heck out of this gun and I don’t know what you’re talking about. It has a dedicated CH channel in the upper receiver that houses the CH. It’s identical to the AR.
      (5) I don’t know enough about the alleged QC issues to opine, but the downside of giving people the ability to tinker at home, you give them the ability to screw it up, too.

      I am glad to hear well-justified viewpoints counter to my own (like Alex’s video tomorrow), but if you are going to conclude rather than opine, please make sure you are up on your facts.

      • Andrew

        A Sig employee reveals himself…

        Check the Sig rifles forum on arfcom. Nothing but complaints…with proof to back them up.

        • Sig guy

          Yes I’ve read them heavily. I’m a self professed sigholic, but even I can’t get behind this as it is.

        • James R.

          Calling you out on literal, factual, objective inaccuracies about the technical specs = “Sig employee”. K. Just ease off the throttle if you don’t know what you’re talking about. Nbd.

      • JumpIf NotZero

        (1) How many “generations” of the MP5 have there been over five decades?

        One. There is one “version” of the MP5 where basically every part from every generation is mostly compatible. Even mags going back to the early prototype days are compatible.

        There are tiny niche variances, but they have never pulled a stunt where they ship a gun and then parts for it are suddenly not forward compatible.

        That happens when you ship a gun that’s clearly still in development.

        • James R.

          What parts aren’t compatible with the MPX gens? Let me answer for you: The mags are cross-compatible. The conversion kits are not. If you own a Gen 1, and you buy a conversion kit, you get a complete Gen2 upper for free. As Gen1 and Gen2 only refers to the upper, not the lower, the lack of conversion kit compatibility is a non-issue since the purchase of the conversion kit gets you a complete Gen2 gun.

          You HK fanboys are getting in a twist over the Gen1 v. Gen2, but none of you knows what it means nor realizes that it’s a non-issue.

          It’s a new gun. There will be improvements, just like every platform ever. Kudos to SIG for undertaking them and making it easy for early adopters to take advantage of them.

        • James R.

          And I don’t know a ton about the 50 year tech history of the MP5, notwithstanding the fact that I have one and love it. But I do know there were numerous “generational” upgrades to it as well, not only with the mags (my MP5 is finnicky with stick mags), but with the bolt, bolt carrier, trigger groups, and etc. HKPro has an excellent timeline of these improvements. So yes, there were “generations” of the MP5, although they may or may not have been designated by HK officially as “generations” as Sig has done.

          And that’s fine. If you want a product to last the long run, you need to continually improve it.

  • JumpIf NotZero

    lol…. Suppress the MPX and the MP5… Then try and tell me the king is dead.

    SIG rushed the gun out the door and it shows. Gen1 be Gen2 issues, QC issues, and no parts availability…

    Once there is an adjustable regulator like it was originally designed for and it suppresses better than a 9mm AR, then you can talk about being the King.

    • mosinman

      the “king” is dead though. except it’s not because of the MPX, but more due to the Short Carbine.

  • West

    I think the MPX is an interesting design and I look forward to some time behind the trigger of a post sample version when one is available locally. To say that the MPX is the new defacto “king of” sub-machine guns less than a year after entering production is a bit premature. The MP5 has been deployed basically everywhere on earth for over 50 years, being adopted by numerous militaries, law enforcement and special forces units. That’s how it earned its reputation as the best submachine gun. The Sig MPX to my knowledge has been adopted by nobody (perhaps some small police deployments I’m not aware of). It’s exciting to see manufacturers designing and producing new submachine guns, but let’s remember that they have either very little or no operational history to base a real opinion on their performance over time.

    • JumpIf NotZero

      To add to that, it’s CLEAR they released an unfinished design and are still working on it.

      Contrast with the MP5’s actual history. Even the CZ Evo has seen real use since 2009.

      I thunk SIG bit off slightly more than they could chew, and had to finally get something out the door to fill orders.

  • hydepark

    I’m glad to hear people not automatically jumping on the ssig bandwagon. Fact is SIG is synonymous with bad quality control these days. My friend has several new handguns including a MK25 and a 239. All of them are garbage with cheap finishes and they regularly malfunction. I would have rather a company put all their money into bringing in and modernizing a US MP5. The Sig, if left in its current configuration, will probably be known as a funny blip on the radar a generation from now. Like others have stated its already in its 2nd generation. And they don’t come close to fixing all the problems. But a quality MP5 clone, an EVO, wait for the LWRC, or…. Well that’s it if you want a decent PCC. I would give Sig much more benefit of the doubt if they hadn’t fubar’d every 550 series they made.

    • JumpIf NotZero

      The finish on the MPX is definitely on my list of perosnal annoyances. The chalky scratchy anodizing they used just… Bleh!

      As to modern MP5, SIG did good with the idea! Excellent with the styling. But IMO terrible on the piston action. A short stroke piston that effectively is ported AT the chamber… Lol. I have serious doubts this gun will ever suppress well.

      The issue I have with the MP5 and clones is that it’s HK based. The part prices are atrocious because you have to buy from HKparts or maybe two others. It’s a scam, but people keep paying it.

      SIG’s prices aren’t much better but the volume is low at least. On the other hand, CZ’s part prices and availability are excellent.

    • Yimmy

      Nonsense and complete utter crap. Sigs may have some poor designs as of late, but their fit and finish on handguns has improved if nothing else since the early 2000s. I’m an HK guy first and foremost, but have owned and continue to own several sigs including those built within the last few years.

      Anyone who spouts off my friends blah blah etc etc hasn’t actually handled a sig and is regurgitating nonsense from 10+ years ago. I guarantee you I’ve seen handled and shot more variety of handguns than you and Sigs handguns are fine.

  • Ian Thorne

    I was onboard with everything except the garbage t-handle charging setup. If it were a side charger I would have one, but the worst charging handle ever made is a deal breaker for me.

    • Anonymoose

      It’s not the worst charging handle ever. There was a reason they went to the T-handle…

      • Giolli Joker

        Well, snag free!

        • Anonymoose

          The original AR10/AR15 charging handle necessitated a slot to be cut over the BCG. Because of the way the AR works, the charging handle and the carry handle heat up during firing, and your sight picture could get blurry and you could burn your finger if you powerstroked the gun.

  • A Fascist Corgi

    You guys keep clamoring for ambidextrous controls on everything, the manufacturers listened, and now the rest of us who hate ambidextrous controls have to deal with extremely annoying ambidextrous safeties messing with our trigger fingers. I really hope that this whole ambidextrous trend dies out and we can go back to having more comfortable firearms.

    • James R.


    • walt

      Can’t believe sig hasn’t come out with something designed exclusively for you.
      Cause everyone is right handed.

      • Green Hell

        Why not to make controls just switchable to the different side with simple dissasembly instead of keeping them constantly on both sides ?

        • Michael R. Zupcak

          Glock Gen4 mag catch style.

      • Giolli Joker

        Well, under fascism in Italy left handed kids were “corrected” (they ended up developing ambidexterity, not bad indeed)… I don’t know if that applied to short legged dogs, however.

      • A Fascist Corgi

        I can’t believe that they’d screw up a design in order to cater to 10% of the users.

    • Mark

      Cool! A nearly 7-pound Glock! Until I can get one, I’ll just hang a sack of potatoes on my Glock.

  • gunsandrockets

    Well, that’s certainly a different beast. Interesting potential in .357 Sig caliber version.

  • noob

    I am curious – what would a sig MPX with a 16″ barrel be like chambered in 22TMC9R? How would it compare to Modern Weapon Systems ION in 22TCM9R and in full auto?

    That’s a video review I’d love to see, along with accuracy and penetration testing.

    • Giolli Joker

      I think the MWS ION uses the full lenght 22TCM.
      BTW, I hope there will be more about it in the coming Shot Show… last year we got a tasty preview, then nothing.

  • BattleshipGrey

    Now I wish I would’ve popped some popcorn before watching the video and reading the comments.

  • Joe

    Looks fun, can’t see it being adopted in any meaningful way. Even the Mexican Military is using 5.56×45 Carbines to take down a Drug Lord. The sub caliber sub gun is dead.

    • JumpIf NotZero

      Defintiely not dead.

      Suppresses much better, logically it’s the same handgun ammo, lighter and easier to shoot, overpenatration is not a concern, among a couple others.

      I’d still pick a 556 in most instances, but subguns are definitely not dead at all.

      • Joe

        Small town SWAT, 2nd and 3rd world Mil/LE units aside, what unit still issues them? There’s much Internet do about nothing as it relates to current use.

        • Giolli Joker

          Like all of Europen police units?
          (Or maybe Europe is 2nd world???)

          • Joe

            Good answer. Now the question is, Why? Why do the Europeans still use a 9mm SMG as a duty weapon?

          • Because 9mm will stop a European just fine, but not necessarily an American?

          • Joe

            Are you referring to the proliferation and readily accessibility of body armor in the United States? Or the different body styles in Americans vs Europeans?

          • Giolli Joker

            I read it as McDonald fed population and laughed.

          • Joe

            Same here but I cried. I truly believe that at every restraunt, grocery, and candy store there should be obese parking spots. At the far end of the lot. Behind a 300′ hill. That is inhabited with Tigers.

          • I was joking.

          • Giolli Joker

            The reason expressed by JINZ, plus the fact that they always did their job, the fact that they’re cheaper and they are already in the armories, the fact that on average the European police is less militarized than the American, the fact that European police can only use fmj.

          • Joe

            So if the only place 9mm SMG’s are still a thing, is Europe and the only reasons is as stated, then what’s the point of inventing a new 9mm SMG/Carbine? (aside from the fun factor)
            Europeans being strapped for cash, and not wanting militarized LE won’t spring for it. They already have plenty existing proven systems in their armories.

          • MNOR

            Norwegian police recently made the switch to JHP. It must be a trick, it’s simply a to damn logical choice to make for Norwegian politicians..

      • Giolli Joker

        I agree on your points, but I’d say that overpenetration is less of a concern, but still a risk with 9mm, especially from the longer barrels of sub guns.
        (Of course there are bullets out there that reduce the risk to 0, but that applies to 5.56 as well)

  • Tim U

    MPX is something I want to like… But Sig makes it hard to with so little parts and mags available to support it.

    CZ isn’t as refined, but at least they have mags and parts already available. All we need now is the gen2 coming in 2016 with 1/2×28 thread instead of the weird threading they use.

  • datimes

    I bought my MPX about 5 months ago. There was a coupon in the box to purchase 3 mags and pouch for the price of 2 mags. There was another 20% off coupon for any SIG product. I bought the collapsible stock for $239. Tax stamp should arrive in about 30 days.

  • Dave

    Looks a bit more ergonomic than my tried and true 9mm Beretta Cx4 “stormlet” subcarbine. Then again, I kinda like the “same controls as a semi-auto pistol” on a “supersized” plastic pistol-with-shoulder-stock. Of course the trigger is a big drawback on the Beretta, but to me that is outweighed by the Uzi-style magazine in the pistol-grip on the “hand finds hand” reloading principle and quasi bullpup layout. Best of all is compatibility with M9 magazines, even if these are much lower in capacity than the SIG or EVO.

    Many users object to the über-heavy reciprocating bolt, certainly. I’m glad there are more subcarbine options than Beretta, Hipoint, and Kel-Tec!

  • Elvis

    The King? I thought this was about the bastardized AR want to be Sig and not the HK mp5. We all know who the king is.