SIG Sauer MCX In 5.56

If you are looking to buy a rifle that isn’t an AR, there are few alternatives. The SIG Sauer MCX is one of the most attractive options in the non-AR market currently. In this episode of TFBTV, Patrick takes a look at Sig’s entry into the piston operated modern sporting rifle segment. The MCX has some rather attractive features like a folding stock, short stroke gas piston, and AR based controls.

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Transcript ….

[coming soon]

Patrick R

Patrick is a Senior Writer for The Firearm Blog and TFBTV Host. He likes guns and has liked shooting guns for as long as he can remember. You can follow Patrick on Instagram @tfbpatrick, Facebook, or contact him by email at

The above post is my opinion and does not reflect the views of any company or organization.


  • Mike K.

    wow that pencil barrel flaps up and down every shot

  • Christian Hedegaard-Schou

    “One of the best Ar alternatives on the market is the SIG Sauer MCX is one of the few good, viable options.”

    You guys really need an editor.

    • Haulin’ Oats

      Have you forgotten TFB is now on a shoestring budget because of Youtube demonetization? It seems Patrick is doing a pretty good job doing this kind of review on the fly, unscripted. No teleprompters.

    • Patrick R. – Senior Writer

      We have two editors that do a fine job. A saved version of the post added some words to the submitted version of the post. We are working on the problem.

      • Bradley

        It doesn’t bother me, but they’re right. Out of any three posts on this blog I would be very surprised if two of them didn’t have grammar, punctuation, or spelling errors. If it’s not a priority then just say so, but it’s not realistic to claim that someone who knows the difference is checking or correcting them in any way.

        • Patrick R. – Senior Writer

          I know nothing about the editing process. I just work here.

  • 8166PC1

    Piston rifles suck

  • EzGoingKev

    Not crazy about the pencil barrel but the like the rest of the gun.

    Regarding the video, you spent WAY to much of the video just shooting the rifle. Think about watching an 11 minute long book review video. Do you want to see 8 minutes of me reading the book on the couch, then in a chair, then in front of the fireplace OR do you want me to talk about the book?

    • 8166PC1

      Pencil barrels keep the weight down and even then the rifle is more then practically accurate.

      • FarmerB

        Depends what you are using it for, personally I’d like a little more meat. Although I have to say I was using my MCX at 600m last week with a 3,5x ACOG and it was pretty effective with Swiss ball ammo.

      • Anonymoose

        Free-floating allows pencil barrels to be as accurate as government profile barrels, but a heavier profile would give better strength, rigidity, and and heat resistance, and fluted heavy barrel would provide superior strength, rigidity, and heat resistance while keeping the weight down, but that would probably add a couple hundred bucks to the cost.

    • Jim N Jenna SK

      Shoot more, always shoot more

    • Patrick R. – Senior Writer

      You see, if I didn’t shoot it that much you would complain that I didn’t shoot it enough and shouldn’t review the rifle. Can’t make everyone happy.

      • BillyOblivion

        Actually, you can.

        They’re called “voiceovers”. Shoot video of you shooting from various angles and doing s*t with the gun, then a voiceover of the the feature or point you’re addressing.

        Then you make the “I wanna see it shot” crowd happy, and the “I want more information crowd happy”.

        • Patrick R. – Senior Writer

          Ill keep that in mind. May or may not change things up in the future.

          • BrandonAKsALot

            I just want to see you throw more guns than you already do. That’s like 70% of the reason I like watching your videos is in anticipation of a firearm being tossed.

          • Patrick R. – Senior Writer

            LOL. It has only happened twice. Might happen again, who knows.

        • Giolli Joker

          “I can’t hear how the gun sounds if that leprechaun keeps blabbering BS about keymod fails and such! Worthless review!”
          (Typical internet comment after the switch to voiceover)

          • BillyOblivion

            If you think you *can* hear how the gun sounds through the…um, let’s be polite here…default microphone in the…well priced digital camera they use, then you are probably, well, yeah, ‘typical internet commenter” is probably about right.

          • Giolli Joker

            That was the joke.

      • EzGoingKev

        Honestly I was hoping for the part of the video where the hot brass caught your truck on fire.

        • Patrick R. – Senior Writer

          Aren’t you nice.

          • EzGoingKev

            Play stupid games, win stupid prizes…

          • Patrick R. – Senior Writer

            Are you the prize?

  • jre92

    Alright I’ll bite with a stupid question, why is the bipod mounted to the top of the handguard??

    • Ehtacs

      Just keeping the center of mass below the rigid support… The rifle hangs from it rather than balance on top of it. This means you don’t need to lock the swivel as much for fixed deployment and, potentially, it’s self leveling.

      • jre92

        interesting, neither heard of nor seen that before until now. good to know!

        • Patrick R. – Senior Writer

          It also happened to be the bipod I had with me that day.

  • mrsatyre

    “One of the best Ar alternatives on the market is the SIG Sauer MCX is one of the few good, viable options.”

    Slow. Down. Proof. Read.

    • Just Say’n

      Not to mention that statement implies the market needs an AR alternative.

    • 6th, 7th grade level. That is what we are looking at here.

    • Patrick R. – Senior Writer

      Looks like a saved version added some words to the version of the post that was scheduled. It happens now and again.

      • Michael R. Zupcak

        All due respect, saying TFB has typos “now and again” is like Democrats saying “we don’t want to take your guns.”

        TFB is one of the most objective gun-related blogs. Unfortunately, the constant, glaring typographical and grammatical errors tend to undermine that integrity.

  • Jim N Jenna SK

    I didn’t like the result of macs testing.. how the bolt carrier rides on two bolts, then add some mud… mud stops the damn machine.

    • int19h


  • John Zie

    How is this their entry into the “piston operating entry segment”, the sig 556 has been around for a decade plus and it’s piston operated…

    • The_Champ

      And isn’t the 556 just a variant of the 550, which is derived from the 1970’s 540?

      Maybe he meant short stroke piston?

      • Anonymoose

        Even then they’ve had the 516 since like 2010.

    • Treyh007

      I think you mean the Sig 516…… I wouldn’t consider the 550 series an AR. That said, Sigs 516 is a Piston AR that’s been out a few years and is what I would consider their Entry into the Piston systems.

  • Cymond

    This is one of​ the most “AR-iffic” rifles that’s not an AR.

  • marine6680

    Not an AR”… But it does borrow very heavily from the AR. Its like an ARs younger sibling its so close.

    Several rifles from other manufacturers are the same way… just a tweaked and pistonized AR.

    And the DI system isn’t really a bad system in need of being designed away like the old post Vietnam era stereotype says.

    • Anonymoose

      And the MCX uppers work on AR lowers (but they will batter the crap out of them unless you get SIG’s vaporware conversion block thing that replaces the buffer tube).

      • marine6680

        Not long back, everyone complained about the AR, then the AWB lapses, and now the popularity has made the industry work to improve the rifle to the point that everyone is copying it.

        Wasn’t it Styer and several other European companies that released “new rifles” that are just AR clones with tweaks…

        And many countries are adopting those rifles or ARs outright. (well M4s anyway)

        Sure, some innovation happened with the new beretta rifle, it’s a little odd to hold, but it’s a new design at least. Some tweaks on it, to slim it down a bit, and I would jump on one.

        The CZ 805 is a new rifle, it’s a bit SCAR like externally, but different inside… and the latest version actually being issues over in Czech, has went to a polymer receiver design, that looks different than the first.

        But most are just copy and pasting and doing a few edits… I just find it amusing.

  • ReadyOrNot

    The Wolf A1 upper based off the Taiwanese military’s T91 rifle, is probably a better and more affordable piston option.

  • ODgreen34

    Looking at the magwell and forward assist and selector switch and the handguard and I am left wondering. How is this an alternative to the AR? I mean I know there are some internal differences but this to me is just another AR. I would think the ruger mini-14 or the fnfal or the AK are AR alternatives. Seems like a nice rifle. Just another nice AR copy to me. Just my 2 cents.

  • Roguewriter

    Hey Patrick, I know TFBTV did a Top 5 AR Alternatives a couple of years ago. Maybe it’s a top worth revisiting?

  • Dave Y

    About how many suppressed rounds did you fire for the testing, and did you do any oiling, cleaning?

    So far, the longest I’ve been able to get a D/I AR to go is 750 rounds without beginning to malfunction, which isn’t terribly bad given how dirty it is.

  • 22winmag

    I prefer the term “internal piston”.

    If you want to see genuine “DI” look under the hood of a Hakim/AG-42.

  • lynyrd65

    I notice some differences from my earlier generation MCX. Mine came with a different brass deflector (not plastic) and a different stock. The barrel profile looks skinnier on the new model too.

    I haven’t done the recall work on mine yet and I don’t plan to. The recall only fixes an issue for people using 300BO with soft primer specialty ammunition. Since I have a 5.56 MCX and don’t intend to use 300BO I would rather retain my flexibility with aftermarket triggers.