RZE Unimag: One AR Mag; 5 Different Cartridges

RZE multi-caliber Unimag

Uniqmag with 7.62x39, 5.56, 6.5 Grendel, 6.8 SPC, and 5.45x39 cartridges. Note the follower with its spring-loaded element to accommodate cartridge stacking angle

A new company called RZE (Ross & Zheng Engineering) is introducing a magazine at SHOT this year that I had a chance to take a look at today. It looks like a standard 30-round AR magazine, but it has a clever follower design that allows it to adapt to the angle of a variety of cartridges in the magazine. As a result, it can be used with no less than 8 different cartridges. The company advertises the capacity to be:

.223 / 5.56mm: 30
.300 Blackout: 30
.204 Ruger: 30
5.45X39mm: 29
6.8 SPC: 26
7.62X39mm: 25
6.5 Grendel: 24
458 SOCOM: 12

The idea that it will work reliably with all these different rounds seems hard to believe, but the company has demo videos showing flawless operation in both semiauto and full auto. I did load one up in 7.62×39, and it was smooth and easy to load up to the 25 round claimed capacity. If it works well – and I am eager to see some independent testing done on it – it will be an ideal magazine for the many modular multi-caliber rifles on the market today.


Ian McCollum

Ian McCollum lives in Arizona, where he spends his time searching out rare, unusual, and experimental firearms for his daily blog at ForgottenWeapons.com. His shooting background is in bullseye pistol, and before becoming a full-time gun writer he worked in the solar power industry.


  • Pretty slick. He should work on making some pmag-compatible followers, too.

    • Risky

      It’s a lot more than just the follower. Looking at the patents it takes a ‘deformable’ shell that fits inside the magazine body thats almost the size of the whole mag.

      • -V-

        Reading the patent, the “deform-able shell” simply refers to the magazine body being springy. Basically, this is no different than any current magazine slightly springing sideways when you load rounds into it.

  • Blake

    If it works as well as you say it does, this is a fine execution of a great idea.

    HOWEVER it also has a higher probability of causing a kaboom if the user isn’t careful, as a lot of these cartridges will fit in a standard .223 bolt face. If I were these guys I’d make sure that it came with copious quantities of warning material; a big red “STOP! CHECK CALIBER” sticker on the side at the least.

    A small addition that would help prevent this would be a little click-dial window on the side containing a wheel in 8 pie-shaped sections. Each is printed with a number or letter & a different high-contrast color, with a reference table underneath (e.g. “B” for blackout, “R” for Ruger, “G” for Grendel, etc.) so that you can set the dial when you load it & have a quick visual indication of the caliber in the mag.

    BTW Eds, it say 8 calibers in the article & 5 in the title…

    • Ian McCollum

      Yes, ensuring that you are using the proper cartridge for the gun is critical, especially with .223 and .300. As you say, .300 in a .223 is bad news, really fast. The company does have rubber-band type colored labels (like the wristbands made for various causes) with caliber markings that you can put on the mags to help identify them.

      • Spidouz

        I know it could cause bad damage, I saw some news about it lately. But I wonder if we could even chamber a .300BLK in a .223 rifle?

        I’m not quite familiar with this caliber (yet) and I don’t have any .300BLK to check, but it seems like the rifle couldn’t even chamber a round because of the larger bullet, does it?

        • Yes…it will chamber…and it will be a very bad day!!!

        • uisconfruzed

          ONLY if the 300BLK isn’t properly crimped. If it isn’t the bullet is pushed into the case and the bolt locks. The pressure has to go somewhere, and your face will be included.

    • Riot

      Isn’t that kind of stupidity also a problem if the fool has two different mags with different rounds loaded if they look externally similar?

  • KestrelBike

    This is pretty cool. Is it just a standard aluminum/steel ar magazine body with a special follower/spring?

    • J.T.

      It would require a custom body.

      • Guest

        I’m relatively sure it uses your standard GI aluminum body.

    • -V-

      Correct. Just needs the custom follower.

    • Plumbiphilious

      So THAT’S how Zheng’s special follower works…
      That’s brilliant.

  • J.T.

    Good in theory. I practice we will have to wait until they are available for independent testing. “Universal” products often end up being universally bad.

  • Craig Black

    Whats the maximum allowed cartridge over all length?

    • Jing

      It is 2.31″~2.32″ OAL.

  • WasThere

    I think the biggest drawback for 762×39 and 68 uppers was good reliable mags, if it works as advertised, this is huge.

  • B

    There was an article on here a couple years ago about a guy developing this exact idea. I hope he is part of this company or he just got ripped off.

    • B

      I see that he is. Good for him. His ideas were very interesting.

  • Amsdorf

    What could possibly go wrong with this idea? The same magazine accepts various cartridges.

    • Dan

      Probably about as much as taking two identical looking magazines with different calibers and mixing them up by accident. It is not any more prone to a careless mistake than any other aspect of shooting.

    • uisconfruzed

      Consider the theory of K.I.S.S.
      The most terrifying sound in the world is ‘click’ instead of ‘bang’.
      The AR isn’t the typical paper puncher.

  • M

    People seem to be fixated on fact that one might load the wrong cartridge for a rifle.

    I’m more impressed on how they were able to add a new dimension to magazines that is more forgiving on geometry. It might be a pretty big breakthrough if it works really well

  • matt RRC

    Product of the year. The 5.45 ability alone is a win for me. Bravo.

  • Vitsaus

    This is the first actually innovative thing this whole week.

  • Mazryonh

    So, are they going to put out one out for larger calibers like 7.62mm NATO or something similar next? Maybe one that can take something like the custom 7x46mm UIAC round?

  • Grindstone50k

    Now THIS is innovation!

  • Colin

    Wonder if they can do this on a six8 Pmag for the longer coal. Can Wssm ,50 Beowulf , 338 spectre ,fit in these ?what about 308 pmag Lr m118 can we get that done as well longer coal

  • Bal256

    Hey it’s that longziz guy! That guy was an unemployed engineer and was attempting to make a bullpup that interchanged with AR parts. He’s been working on that magazine for years. I thought it was just a hobby, but I’m glad that something he made is now out on the market.

    • -V-

      Indeed! I think first saw his post about this in ’08 or ’07. I’m glad that this is finally coming to market. On a side note, suddenly makes 7.62×39 ARs a lot less onerous!

  • Scott P

    Too bad I don’t currently own or foresee myself buying a gun that would require this mag unless new gun designs come out in the future that take advantage of this.

    Otherwise I am impressed and hope the company succeeds becoming a household name like Magpul.

  • Darren Hruska

    This is perhaps the most interesting AR-15 related product I’ve heard about in a very long time. Here’s hoping that this magazine is reliable from the time it’s unpackaged to many years after. . .

  • uisconfruzed

    Due to the different case diameters the feed lip configuration is critical and it’s one of the main reasons for semi autos to FTF. They’ve done a GREAT job of engineering the follower. I want to see A LOT of test reviews.
    If RZE Unimag would like to send me a test mag I can run it through it”s paces on 300BLK sonic and sub, 5.56 and 6.5 Grendel.

    RZE Unimag
    RZE UnimagSigned, patiently waiting.

  • uisconfruzed

    Excellent demo.
    His pistol holster prints horribly, which one is it so I don’t pick one up?

  • Jing

    Have to travel today. Will do next week! Thanks and have a good weekend!

  • roguetechie

    I’m buying a ten pack of these for two equally important reasons.

    1. I shoot a wide variety of calibers and preferentially use stanag magwells when possible, (and g3 mags where possible for midsize cartridges). So by using these I don’t have to play follower hockey.

    2. LONGZIZ #1!!: Zheng buddy get it to market for under $1500 not including your stripped lower so you don’t need an 02/07 SOT.

    I want some seriously high quality products to be out there when I start releasing mine! Good competition is extremely good for the customer, and drives innovation.

  • Aklover

    So it has a tilting follower? Everything old is new again

  • Edward Franklin

    I’m rather interested if this isn’t the magazine solution that Faxon alluded to when they talked about their 7.62×39 ARAK. If this works as advertised this would be huge.