Ready for Any Mission: SIG Sauer MCX Virtus — Full Review

As SIG SAUER’s plan of global domination progressed last year, the world was treated to an entirely new rifle in the MCX. A lot of the press went to the smaller, pistol-sized MPX, but the MCX did make waves. It became the duty weapon of the Netherlands Maritime SOF, the British CTSFO, the Berlin Police, and is in contention to become the official issue rifle of the French Army. Never a company content with good enough, SIG gathered data from all the real-world end users and are releasing an improved version — the MCX Virtus.

Brief Background

The Virtus is billed by SIG Sauer as the “most adaptive, accurate, longest lasting rifle available.” The company further states that the rifle was conceived for the demands of the Special Operations community. Well, good news, I was one of those. Now for the bad news. We tend to be incredibly skeptical of anything this new, especially once you look at the operating system. So it was with a wary eye that I unboxed my MCX Virtus Patrol.


  • Type: Gas-piston operated semiautomatic
  • Cartridge: 5.56x4tmm NATO
  • Barrel Length: 16 in.
  • Overall Length: 35.5 in.
  • Trigger: 4 lbs. (tested)
  • Weight: 7.9 lbs.
  • Sights: none
  • Finish: Gray
  • Capacity: 30+1 rds.
  • MSRP: $2,233
  • Manufacturer: SIG Sauer

Now before I get crazy, I want to say upfront the MCX had two things pinging my radar. First, it is a piston-operated gun. Second, the bolt and recoil system is a serious departure from anything else I have seen. I have run the SCAR light, the ACR, and several piston models. Most piston guns, like the H&K 416, are extremely front heavy and the recoil kicks like a train wreck. Even when they’re chambered in 5.56, which is saying something. And any variation I have seen that tries to eliminate a buffer and buffer tube has a trade-off. It’s not that I don’t believe an AR system can be improved on, it’s just that you can only sell me the Brooklyn Bridge once.

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Range Time

Fortunately, a trip to the range dispelled any misgivings I had about the recoil of the SIG Sauer MCX Virtus. Not only was my Virtus incredibly accurate, it handled like a dream. I was amazed by how well SIG’s system soaked up recoil, making this one of the flattest shooting rifles I have picked up in 5.56. Even with a simple three-prong flash hider, the Virtus recoiled like an AR with a competition level brake. The difference might not mean much to the casual shooter, but for the intended audience, that means more rounds on target faster. And details like that matter when you are trying to surgically shoot terrorists in an S-vest factory. The rifle snapped between targets easily, with no hint of imbalance. The rifle is slightly front heavy, but not obnoxiously so. This probably owes more to the lack of weight in the rear than any significant mass of the piston system.

Accuracy wise, I was impressed by the Virtus. I only had a 6X scope available this week, so I shot my groups at 50 meters. Not the norm, but its what I had. With SIG Sauer Elite Performance 77-grain OTM loads, the Virtus turned in multiple ½ inch groups. This is not a 100-percent value of the max accuracy in the gun, but it does tell us it should be an inch or under at 100 meters. For a battle rifle, that is more than adequate.

The controls and pistol grip are AR familiar, which makes the learning curve picking this rifle up a flat zero. But that is really where the similarities end. The buttstock is a skeletonized and the lightweight five-position stock also folds to the side. In case you were wondering, the rifle remains fully functional with the stock folded. Instead of a buffer and buffer tube, the recoil system is housed inside upper receiver. The trigger is the new SIG Matchlite duo trigger, as in two stage. My test sample’s trigger broke at around 4 pounds and is a night and day improvement over a standard mil-spec trigger. Twin recoil springs r the de over top of the bolt, which is also MCX specific. The bolt is about half the length of an AR bolt, and also doesn’t have to travel as far, which likely contributes to the soft recoil. This makes the MCX upper about a ¼ inch taller than a standard AR, but it is not something you would notice unless looking at the two side by side. Lefty’s will be stoked to learn that the MCX has an ambidextrous fire selector, magazine release and charging handle.

The handguard features plentiful real estate for M-LOK accessories and has a nice oval shape to it. I really appreciated the smooth sides and skeletonized structure while I was conducting run-and-gun drills. The piston system is adjustable for suppressed/regular shooting, with a large cut out in the hand guard for adjustments. The Virtus is advertised as user adaptable. The handguard is ingeniously designed to be easily removable. The hand guard has machined rails that overlap the upper receiver section for strength, and is held on using the front takedown pin. This not only gives you an extra 5 inches of rail that is actually part of the upper receiver for optics, it makes handguard swaps easy. Which you may want to do when you swap the barrel out for a shorter one or a different caliber.

Wait what? Yeah, barrels are user swap easy too. Even for those of us that suck at shade-tree gunsmithing. Provided you have a Fat Wrench at home, you can swap barrels in under a minute.  There are two captured screws under the hand guard, size T27. Unscrew those and the barre will slide off easily. Put on a new one, torque to 60 inch pounds, and you are good to go. On the subject of barrels, the Virtus does feature a design change over the older MCX. The new profile is a heavy taper barrel, designed to enhance accuracy. It is thick in the back, and tapers to near pencil thin at the muzzle. I haven’t shot a lot of rifles like this, but the accuracy above tells me it is working. You can switch to .300 AAC Blackout right now, with hopefully more caliber options on the table in the future.

Overall, I’m impressed by the SIG Sauer Virtus. If the MCX system holds up as advertised, it represents one of the greatest leaps in battle rifles I have seen in my lifetime. SIG advertises 20,000 rounds before any parts replacements, and we just might have to find out if that holds up. At the end of a gun review, it’s not often that I ask for an extension to the loan, but this is an exception. I really want to see how this gun does over time, and in some adverse conditions. Winter is coming, and with a bit of luck, SIG will let us beat it up till Christmas.

For more information about the SIG Sauer MCX Virtus, click here.

For more information about SIG Sauer Elite Ammo, click here.

For more information about the Fat Wrench, click here.

To purchase a SIG Sauer MCX Virtus on GunsAmerica, click here.

About the author: Clay Martin is a former Marine and Green Beret, retiring out of 3rd Special Forces Group. He is a multi-decade and -service sniper, as well as 3-Gun competitor and Master ranked shooter in USPSA Production. In addition to writing about guns, he is the author of “Last Son of The War God,” a novel about shooting people that deserve it. You can also follow him on twitter, @offthe_res or his website,

{ 18 comments… add one }
  • Straight Shooter November 7, 2017, 3:46 pm

    Stop playing around! Get a Battle Rifle, the original “Black Rifle” FN FAL

    Legend of Old Dirty 08/09/2014. Round count is approximately 16,500.

  • Dreadog November 7, 2017, 2:44 am

    What a bunch of haters, wieners, ingrates and scudo military dorks. If the gun community had you all attitude we would still be shooting muskets and never even evolved to the revolver. I’m all for innovation or at least some one trying to think out of the box. Hey its how this country got so great. Thanks Sig Sauer.

  • Russ H. November 6, 2017, 4:19 pm

    Sweet! I want a couple! OK, one. Nice design and I especially like the interchangeable barrels – it\’s about time someone did this – of course it was Sig.

  • Mark Wolfson November 6, 2017, 2:23 pm

    You of all people should realize that 5.56 Nato is a non-starter for modern defense. Please do not show us anything lower than the number 7.

    • Frank Furter November 6, 2017, 8:10 am

      Then I’m sure you wouldn’t mind getting shot by one, right?

    • Twisted Panties November 6, 2017, 9:20 am

      Ahhh yes the venerable Russian Tokarev 7mm. Much better choice for gun battles than a 5.56 round.

      “please don’t show us anything under a 7”. Most soldiers who saw combat didn’t have gun fights over 30 m. and rarely over 100. Well within the effective range of a 5.56 bullet. Anything over 7 is a waste of money, has slower follow up shots and higher recoil making it less easy to control. When’s the last time you saw combat brother? In your deer stand drinking Busch Light at 0400?

    • Just a guy November 6, 2017, 1:02 pm

      6.5 x 39 Grendel and 6.8 x 43 Special Purpose Cartridges are great calibers for the AR-15. Both of those rounds are effective to at least 330 yards with a 16 inch barrel.

      I personally do not care for the 5.56 x 45 round. I am in process of acquiring a .300 Blackout AR-15 with a 16 inch barrel. Using supersonic 110 to 125 grain bullets in .300 AAC Blackout rounds give you a rifle effective to around 275 yards.

      • Rick December 16, 2017, 10:24 am

        I agree using the 6.5 or 6.8. I like the Creedmore round. I prefer .308 for its longer reach but having smaller cals like 6.5 or 6.8 to swap in would be useful. Btw, 300 Blk is pretty expensive! 5.56 or .223 is much cheaper for the range and it’s got takedown power. I love my MCX

    • Treemaniac November 6, 2017, 4:04 pm

      Funny I bet your wife says that all the time! lol

    • Russ H. November 6, 2017, 4:21 pm

      Mark: Swing and a miss. No you don\’t need a \”7\” in front. Ever been to combat and shot someone with a 5.56? No? Try it before making silly comments like this.

  • Bryan November 6, 2017, 10:49 am

    Until next year when Sig goes another direction and discontinues support for it.

    Keep SIG burned enough

  • Treemaniac November 6, 2017, 10:36 am

    Nice review Clay, love how this rifle comes apart. Hats off to Sig for trying something new, reminds me of the Para FAL’s bolt system. I’m so sick if hearing comments about 5.56 not being a good round for home defense, and how you can build a 1moa AR for a grand. If we all thought the AR was the end all for rifles how will newer, better design`s ever be made? I smiled when I heard the sound of kids in the background… Imagine having Clay as a Dad? I mean his kids are guaranteed to be bad asses!

  • Big John November 6, 2017, 10:30 am

    …I was driving through Connecticut and heard a whole bunch of popping sounds the day this rifle was rolled out, took me a minute to realize it was all the ass holes slamming shut at the Colt factory. Anyone experience a similar event in South Carolina at the FN factory??? As usual- nice review Clay, thank you.

  • Theron Ballard November 6, 2017, 9:22 am

    My bet is that this is proof of concept stepping stone to a 7.62×51 rifle that competes for a new Army requirement. Would love to see it scaled up with all the same attributes.

  • Me November 6, 2017, 9:09 am

    Cool rifle, not sure why the military would want one., Over a pound heaver and more than double the price. Only difference i see would be the folding stock. Am I missing something here?

  • Mahatma Muhjesbude November 6, 2017, 8:57 am

    I started ‘yawning’ as soon as I saw it. Before I even blink at the sticker shock of what something like this will cost to the collector, I can say that you can put together a sub moa tac driver these days that’s about as reliable as you can get all with aftermarket enhancement goodies and whistles, and bells, for probably less than half of what the civilian version of this Sig will cost.

    And who cares if it will last 20 thousand rounds? Not the average citizen? Modern warfare doesn’t wcwn care about that much anymore either.

    I realize most people here have never been in serious firefights in an ongoing war but if you ever were you’d know, that contrary to the movies, that the average infantry engagement doesn’t last long enough to worry about if your barrel will burn out or not, LOL! In other words if you’re in a hot exchange of small arms fire, and nobody won yet after you expended a good portion of your ammo, and you don’t yet have your Arty or Air or Drones or some other heavy equipment joining in fairly quickly to give you the ‘cutting edge’, you usually fall back and start over later.

    And future ground wars will not be fought with personal battle rifles much over CQB ranges, like less than 100 meters for urban house to house combat or similar anymore. So the sub moa factor is moot. And the weight is still too much for a personal CQB combat rifle considering how easy it is these days to use other materials to lighten things up. Further than that range will handled by robots or squad deployed armed drones or fifty cal or 20mm single man carry smart weapons that can’t miss. New compact high capacity 20 mm grenade launchers more explosively powerful than the old 40s, And further than that, well, Your squad target tech Sgt. will probably have a drop menu on their wrist computer to order up any number of heavier duty side orders the team might need to quickly solve the problem.

    So I don’t know what Sig was thinking here. But it certainly wasn’t pragmatic modern infantry warfare. Maybe it’s a last ditch effort to regain it’s former status again or something?

    And, Yeah, Clay, make sure you document all the jams and glitches when you’re ‘testing’ this thing. And I hope you’re using a military full auto version so you can replicate reality firing conditions. And do the exercise of dropping the right side of it with the ejector door open and bolt back and mashing it around in the sand on that side like a soldier might do if he was diving around in the ‘dunes’ for cover after just firing, and then trying to fire after that a few times??? Anytime I see a rifle with more than two springs in the bolt carrier recoil group I get nervous.

    I seem to remember that this was tried way back, maybe by FN and maybe that’s why they went with a spring on the piston rod AND one on the bolt, instead???

    So I’m not sure why Sig

    • Comanche January 23, 2020, 10:06 am

      How refreshing hearing from a long-winded, been there done that, got the T-shirt Rambo type!!!%🇺🇸

  • John Snyder November 6, 2017, 7:54 am

    Sorry, but I use 5.56 for HD
    Carried it’s Papa in ‘nam, along w/ M60 and M79 or w/ 40mm launcher on the M16.
    I just used what I could get ammo for each day and where we were patroling. Real world experience w/ results.

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