SIG 556xi Rifle 7.62x39mm, 5.56mm and .300 BLK

SIG Addict got hold of a photo of SIG SAUER’s upcoming SIG 556xi modular rifle that will be available in 5.56x45mm, 7.62x39mm, and .300 AAC BLK. The barrels and bolts will be swappable between calibers. According to SIG Addict they can accept AK and AR magazines (how this is achieved is not specified). The models available will be

SIG 556xi – Standard model, comes with standard side-folding stock (with removable cheek pad)

SIG 556xi Carbon – Enhanced model, comes with carbon fiber quad rail, and skeletonized side-folding stock

SIG 556xi Russian – Similar to standard model but chambered in 7.62x39mm Russian only, comes with standard side-folding stock (with removable cheek pad)

SIG P556xi – Pistol model, comes with quad rail and SB15 forearm brace


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.


  • I’ll say it before somebody else does. Get rid of that cheek piece–it really detracts from the looks of the rifle.

    • wetcorps

      Haha very true.

    • txJM

      It’s remove able.

      • That’s good. I don’t imagine you would need it all the time.

        • Sergeant Raven

          You do.
          At least I do. For iron sights or Optics (AR or lower 1/3), you still need it.
          And really, “look” vs. “functionality”?
          One of the most functional riser I was fortunate to try was a leather pad, strapped to the buttstock with canvas buckled belt. It was a Soviet-made SVD, and that cheek riser was one of the ugliest thing I’ve ever seen, but did a great job at mid-to-long range shooting.

          BTW, current SIG556xi (5.56 “standard”) owner here. Aimpoint CompM3 on GI (M4) QD mount and PA 1-6x ACSS with PA DX cantilever, besides of the stock irons.

    • erwos

      Wow, guessing you aren’t a Sig 556 owner?

      That cheek piece is the SELLING POINT of those rifles. It gets your line of sight high enough to use “normal” AR-15 optics and BUIS (as shown!). I’d buy two in a heart beat for use with my 556 and 556R.

      • dp

        Very correct observation. Look at nearly every shouldered straight-stocked AR. There is always portion of butt plate sticking above shoulder. Why? Lack of proper cheek support. SIG knows what they are doing.
        On top of, this particular system being ‘AK in tuxedo’ is possibly better overall than typical AR; specifically in ruggedness and adverse reliability terms.

        • Curious_G

          So…they are slapping a riser on a stock designed around lower sights so they can use the wrong sights.

      • Nope—- I can’t speak to the function just the look.

      • Curious_G

        Or…use sights “normal” for this gun and not designed for an AR. The sights look as ridiculous as the cheek piece.

        Why sig refuses to just put quality Sig 55_ series sights on the rifles it sells here is beyond me. Another reason why the 556 was never what it should be.

        And yes – I am a 556 owner.

    • Nicks87

      I agree, I’m sure it’s more for function than looks but it does make the rifle look cheap. Hopefully the skeletonized one looks better.

    • anthony

      It is removable

    • Sammy Busby

      I dont care for the cheek piece either and think it would look better without it. Maybe its removable?

  • floppyscience

    Absolutely hideous. It looks like something photoshopped together.

    Does SIG even sell enough 556 rifles to justify this new modular version? Or is it an attempt at revitalizing the line?

    • It’s anyone’s guess. Honestly I don’t see many Sig AR’s in stores with the exception of Wal Mart.
      My guess would be a jump start product to give shooters more choices in calibers in a kit form perhaps.

    • st4

      My first thoughts exactly. Put a bag over its head before it breaks a mirror. Can we please get a true 550 now, Sig? Now that was a thing of beauty.

      • erwos

        There’s no market for a true 550, as evinced by the failure of the 551A1. Maybe there’s a market for a 556 with welded diopter sights, 20″ barrel, and a decent scope rail on the receiver, but even that’s a stretch.

        • st4

          That’s exactly why I didn’t buy a 551A1, it was close, but still not 1:1. There are the pre-ban examples of what I’d want floating around but their prices are astronomical.

          • erwos

            I have heard, but not tried, that you can use a 556 upper on a 556r lower with metal Galil mags (presumably, a few minutes with a file could get Orlites working). I have tried a 556R upper on a 556 lower with 7.62×39 AR mags, and it did feed properly in my limited testing.

    • txJM

      That is just the AK version. There are more photos at the source link.

    • gunslinger

      it’s like an ar and an ak had a kid..and that kid had a kid with an ar, then that kid had a kid with an ak..

      the arakar471547?

  • Graham2

    Sauer not Saur!

    • Yea I know I’m still editing—– We’re doing ten and twelve hour days around here getting ready for SHOT and still keeping the articles coming:-)

      • Graham2

        Sorry Phil, I appreciate your hard work. Guess I’ve woken up rather grouchy this morning.

    • Beju

      Correct. The SIG Saur is their new reptilian mascot 😉

  • Raven Steeler Man Arceneaux

    Do Over ASAP

  • Vhyrus

    I don’t care what it looks like. If it does what they are claiming, I’m in.

  • TangledThorns

    SIG is all about the modular this year.

  • Tim U

    I want to like it, but I just can’t bring myself to do it. Very ugly, and will it be any better than the existing Sig 556 line? I’ve seen some really mixed views on them that would make me hesitant to drop the cash needed for a Sig rifle. The 556R was interesting to me until I saw the horror story Military Arms Channel found with them.

    • st4

      From what I hear current 556R’s have all the bugs worked out, but first impressions certainly can have a long lasting effect on the market.

      • Curious_G

        … and that is the problem. The early Sig 556 had so many problems (and were priced through the roof) that plenty of people walked away.

        I am one of the lucky ones I suppose. I have an early one with the updated optics rail and mostly swiss internals/gas block. I wish it accepted a swiss folder (it is the stupid M4 buttstock variant), but other than than a wonky front flip BUIS that walks I have never had a problem to speak of.

  • Beju

    Wow. That’s really, something.

  • erwos

    Sig 545xi in 5.45×39. Make it happen, Sig.

  • Joe

    I wonder what the price will be on this. If it’s cheaper than a Tavor, I might go for one of these instead (if the reviews are good, of course).

    • Um I imagine it will be a bit more expensive

      • pewpew

        I don’t believe it will be more than a Tavor – “will be replacing all of the previous SIG 556 variants on the commercial market”. Current market price for a 556 Swat Patrol is ~$1300 (and . There is no way the market will stomach a price increase of $700+.

        • pewpew

          No edit button edit: Last I saw on the Sig website, the MSRP was the same as the MSRP of the current 556s. They’ve removed that now but the gist is a replacement for the current line of rifles isn’t going to carry a ~50-60% price hike, unless they don’t want to sell any guns.

  • Seth Hill

    I have wanted a 556 for a long time, one with the side folding adjustable stock. I thought they did the wrong thing getting rid of them and going with the 551, it always made more sense to utilize common AR magazines over proprietary ones. I will have to wait for reviews and testing before I drop money on one of these.

  • ColaBox

    So…how’s that MCX PDW coming Sig?

    • LCON

      Guess about as well as the Magpul PDR.
      Seriously though MCX looks hot SIG lets see some action on it please

  • Nathan Means

    I have to disagree with all the “ugly ” posts. Look at the glocks when they first came out. I really like the idea of switching bolts and barrel with the ability to use multiple mags… Ive always wanted a nice ar plarform to use 7,62×39

  • noguncontrol

    more rifles, yippee!

  • dude

    Ummm, SIG released the 556xi 6 or 7 years ago. If hadn’t only had 2 years on my 556 at the time, I might have changed up. The only I don’t like about mine is the charging handle on my strong side. Of course, being a 556, the upper is the serial numbered part so I couldn’t just get a new one.

  • Sammy Busby

    I would love to have one of these babies!