Hail Hydra. MGI Multi-caliber AR

MGI made an AR that is multi-caliber. So what, many other companies have a multi-caliber AR. Well this can switch from 9mm – 7.62x39mm – 556 within minutes and without any tools. Check out MGI for more info.

Nicholas C

Co-Founder of KRISSTALK forums, an owner’s support group and all things KRISS Vector related. Nick found his passion through competitive shooting while living in NY. He participates in USPSA and 3Gun. He loves all things that shoots and flashlights. Really really bright flashlights.

Any questions please email him at nicholas.c@staff.thefirearmblog.com


  • Bradley Chapman

    If you’d like a cheap, flimsy, rattling mag well, canted barrel, multi caliber rifle for under 1,500, look no further.

    • JumpIf NotZero

      If you want to spend all day re-sighting in your range toy – look no further.

      No serious shooter would want that level of modularity on a tool they had to trust their life on. Even for home defense I wouldn’t want any of that.

      • Jack Morris

        Not every rifle is intended for home defense. There are a ton of benefits to having a multi caliber weapon that go beyond protecting the homestead for break-ins.

        I would consider myself a pretty serious shooter and I would love to have this kind of modularity. You are entitled to your opinion, but dont make the mistake of thinking your opinion is shared by everyone else.

    • Bradley have you ever shot one or handled one? I ask because a group of us shot these a lot at the Big 3 a couple of months ago. No rattle not cheaply made and they were as accurate as most any other AR. About 30 of us shot one during a competition we had and it performed just fine for everyone. As long as you sight in the rifle using the front sight it’s still on target when you come back to that caliber.

      • Bradley Chapman

        I was able to handle this weapon at a local gun store. I was even able to swap out the mag wells. Both of them had quite of bit of play and audible rattle upon gentle manipulation of the rifle. The supplied barrel was canted to the right ever so slightly (this is most likely a factory defect) on the 5.56 barrel. The 7.62 barrel was fine. Upon cycling the weapon I found the bolt felt quite gritty and felt a bit cheap. The charging handle itself had an incredible amount of play inside it’s track. I have no doubt that the rifle you fired months ago performed admirably but my first impression of this $1,200 rifle have left a sour taste in my mouth.

    • vonzeitgeist

      I had one to evaluate for a security company working overseas. They thought the option of being able to use both locally sourced mags and ammo for convenience, and western spec when the contract called for it was great. I bought it from MGI not telling them it could mean a largish sale.

      The 556 barrel was OK, it was a VERY heavy AR but the lock up seemed solid enough. The 7.62 barrel was unmarked (a safety issue if you were going to have both) and threw bullets sideways when it ran at all. Sent that back and got a replacement a few months later. It simply would not run, though when I did feed rounds in manually they now went straight. Failure to feed no matter what AK mag I used. Sent it back for repair and heard nothing for several months. Made several phone calls, always answered by a pleasant woman who promised I’d hear as soon as the tech came back from one place or another in a day or two. Never happened.

      After 9 months I decided we had our answer and so asked for a refund.
      Sent the 5.56 parts back and now they had everything. By the time we got
      the money back the ordeal had lasted about a year and had involved the
      BBB and Visa. The gee-whiz factor of having this is not worth the chance you take in dealing with MGI, I think.

      Don’t think about shooting two calibers on a range day as the barrel and gas tube get too hot to handle quickly. The gas tube stays with the barrel, so you’ve got a flimsy aluminum tube wobbling out there in the wind as you try to thread it into the receiver and that must be stored carefully when not in use to avoid bending it. Cool idea that’s been kicking around for a very long time and seems to pop back onto the radar every few years. Not recommended.

  • gabrek

    I’ll buy one if they make a front-end that accepts a Colt LE 901 .308 upper.

  • John

    $600 S&W AR
    $500 Saiga AK
    $500 Rock River 9mm upper
    Total $1,600

    • John where are you buying a S&W AR for $600 bucks? I need to find that place!

      • YAY

        Or a 500 dollar Saiga AK. What, before conversion?

      • HSR47

        I don’t know about him, but I know of a store in the Philadelphia area that sold somewhere around 500 S&W M&P 15 sport rifles for under $560 each within the last 2-3 months…

        It’s a certainty they got a fairly good volume discount, because I’ve seen what *my* dealer can get them for, and there’s no other way that they could have turned a profit on them.

  • Jack Morris

    I see a lot of people here poo-pooing this rifle.
    I for one, think this looks like a fantastic modern survival weapon. Since when does having lots of ammo choices in the same platform equate to a negative thing?! In the land of politically determined ammuntion availabilty, having a rifle capable of several effective calibers would be invaluable!

    I swear; the gun community will find anything and everything to bitch about.

    • HSR47

      While I understand where you’re coming from, I believe that you’re wrong.

      First, I’ve handled a handful of these. As AR-15 pattern rifles go, they tend to be heavier, more expensive, and use more proprietary parts than most basic AR15 rifles (Colt 6920/S&W M&P 15, etc).

      For what I’ve seen these go for configured in a single caliber (and especially once you factor in a conversion kit) you could practically get a decent AK (e.g., an Arsenal or similar) and a decent AR (Colt/S&W/BCM/etc.). At that point, you’d have two complete guns for roughly the same amount of money as the Hydra — not only that, but each individual rifle would be lighter than the Hydra. Remember, ounces = pounds, pounds = pain; if you have to hump a rifle and gear around, lighter is better.

      The resulting pair of rifles should also be entirely devoid of proprietary single-source parts, which means that if/when something on them breaks, finding a replacement will be far easier.

      Furthermore, assuming that if/when things to hell in a handbasket as you imply, you’d have more functional rifles; In a situation without the rule of law, having more functional firearms is always a plus.

      On the whole, this design seems like a gimmick to me; Outside of those with registered drop-in auto sears and/or registered lightning links (where switching between host guns can be a PITA), I don’t see much practical use for this.

  • 1leggeddog

    would this also do .308? like an AR-10? (With a different upper of course)

  • iksnilol

    I don’t get the hate. This is what the AR should have been from the get go – true modularity.

    • HSR47

      To put it simply: Weight + proprietary parts + expensive.

      I don’t hate it, I just don’t see anyone other than RDIAS/RLL owners benefiting from this particular design.

  • mechamaster

    Aww.. this AR cannot accept the underslung grenade launcher. Lol.

  • ducky

    Handled them several times at shot show. The AK mag well does not offer any front support (top) just like any other conversion I’ve seen or the SIG 556R for example. So the magazine can tilt forward/upwards, at least when the bolt is open. Given the fact that the mag is doing this under recoil (mass inertia) I wouldn’t trust this regarding reliable feeding …

  • Sam Schifo

    I find it odd that Bushmaster and FN could have cornered this market with their respective ACR and SCAR platforms, except that neither one has made a conversion kit available to civilians yet. I don’t get it, why design a rifle around being modular, if you aren’t going to make anything available for it? I would rather have this than an ACR or SCAR, you can actually get the conversion kits for it and it takes many standard AR-15 parts.

    • echelon

      Agreed. FN has barrel kits for the SCAR now, but guess the price? $1000! I personally run an ACR and love it because I’m a lefty, but yep Remington/Bushmaster have killed it. There is a strong grassroots following for the ACR and they are making aftermarket parts but since they are low volume, custom parts they are pricey. It’s a shame really.

      So yes, this Hydra is a good idea to start, but once again they forgot to make it completely ambidextrous right out of the box so for all of it’s modularity it still loses design points because they couldn’t think far enough to include a true ambi lower.

      Someday we’ll get there. The Sig556xi and Beretta ARX100 are steps in the right direction. As long as they get the conversion kits out to market quick and at good prices they will be winners in the market.

      If the decades old design Tavor can be a hit in the market just because IWI did a good job making it available at a reasonable price and being fairly quick to market with the 9mm conversion kit then anyone else that does just a smidge better should be good to go!

      • HSR47

        From what I’ve seen/heard, Remington/FG/CCM have been treating the ACR as a red-headed stepchild.

        They’ve been talking up conversion kits/barrels in 5.56 and 6.8 since they first brought the rifles to market, and they’ve perpetually been 6+ months away from being ready.

        When I spoke to some reps at the GAOS in Harrisburg this year, I was told that the most recent delay was largely because the last panic and/or other contracts were using all of their barrel manufacturing capacity. When I asked about .300 blk barrels, I got the impression that they didn’t think there would be any demand, and as such they didn’t have plans to make any.

        I do agree though, that if they (or someone else) could actually get around to making parts, the ACR would be a neat platform to use.

        • echelon

          Indeed. It’s a shame that anything Freedom group/ROC touches withers and dies…

  • Cymond

    I like the idea of the lower, but would prefer separate uppers for different calibers. The only upper parts that all of the calibers have in common is the upper receiver and the handguard. For all of the trouble of switching barrel and bolts, I really think separate uppers are more practical.

    I like the idea of the lower but they’re just SO expensive. The base lower is $100, and each mag well is $275. Heck, $375 for one caliber get you into a very premium lower, and when you add the 2 other magwells, it brings the system cost up to $925 just for the stripped lower!

    And that’s not counting all of the other parts for a caliber conversion.

  • Bud

    Thank you on your article about the Remington recall trigger problem.Remington informed me,that they have ordered new triggers for the better fix.