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Windham Weaponry will be unveiling its new RMCS offerings next week at SHOT Show 2016. I’ve added them to my list of booths to visit, but the short story is one AR-pattern lower receiver with swappable magwells, and a quick-change barrel system in the upper receiver. Kits are offered with all of the parts needed to rapidly swap between two (.223 and .300 BLK), three (.223, .300 BLK, and 7.62×39), or four (.223, .300 BLK, 7.62×39, and 9×19) calibers. I assume caliber conversions will be available separately for people who start with a two-caliber kit and want to expand later, but that isn’t mentioned the following press release and product video . . .

See the Revolutionary Multi-Caliber System at the 2016 SHOT Show

Windham, Maine (January 14, 2016) – In one of the most exciting announcements to come from Windham Weaponry since its inception in 2011, the Company invites attendees of the 2016 Shooting, Hunting, and Outdoor Trade Show (SHOT Show) to visit them in booth #10376 to see their new multi-caliber AR Platform rifle series. The Windham Weaponry Multi-Caliber System (MCS) is a groundbreaking new rifle that allows the user to convert between calibers by changing out the barrel, magwell, and bolt carrier group and utilize the same lower and upper receivers. The MCS is available in three configurations, and offers up to four caliber options in one AR platform rifle.

With only a few simple steps, change between .223 Rem.-5.56mm NATO, .300 Blackout, 7.62 x 39mm, and 9mm calibers.

  • RMCS-2: .223 Rem.-.5.56mm NATO / .300 Blackout calibers
  • RMCS-3: .223 Rem.-.5.56mm NATO / .300 Blackout calibers / 7.62 x 39mm
  • RMCS-4: .223 Rem.-.5.56mm NATO / .300 Blackout calibers / 7.62 x 39mm / 9mm
Manufacturer’s suggested retail price on the RMCS AR Platform series ranges from $1,738 to $2,971.

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  1. An interesting concept for modularity. I wonder if they are perhaps working on a .308 option as well.

    • If they did it would probably be a different system for the larger AR calibers like .243 and .260 and the like. Might be fairly popular with hunters.

    • An interesting concept for modularity. I wonder if they are perhaps working on a .308 option as well.

      This looks like a rebranded MGI Hydra system, and MGI has promised a .308 version since at least 2012. You can find a bunch of videos about it on YouTube. Like this:

      I still haven’t seen them released. I wouldn’t hold your breath.

    • Concept? Hell they have been sitting on this for years. Cobb manufacturing used to build these until they were bought by bushmaster in 2008. The caliber they had put these 4 to shame. If I remember correct it went from 22lr to 308, if not magnums. Worked buy changing mag wells and then upper options. Anyways bushmaster was sold to Cerberus group in 2011. The original owners of bushmaster then built a new gun company Windham rifles. So the owners who are building this “new” platform had bought it ready to go about 8 years ago.

    • Robinson Armament has been doing this for a while now. The XCR-L is designed to fire small rifle rounds 5.56 NATO (.223) , 7.62x39mm, .300 Blackout, and 6.8 SPC
      and the XCR-M medium long rifle rounds 7.62 NATO (.308), .243, .260, and 6.5mm & 6mm Creedmoor

    • Um…maybe I’m missing something but isn’t 7.62 the same as .308? I know most if not all 7.62 platforms that I have looked at will fire a .308 round.

  2. $3,000? Seems more expensive than 4 uppers/rifles?. It would be interesting to see if they figured out the bugs in the 7.62×39. I’d love to have a kit in 5.56,9mm and 7.62×39. More Barbie for men. *** I see what they did, got rid of those crappy modded AR mags and went AK mag. Smart.

    • MSRP $2,971, but who knows what actual street price would be. $2,500? There are obvious advantages to having separate rifles, and some to having a single firearm that takes many calibers. Depending on where you live or how many guns your wife allows you to have 😉 , one gun w/ lots of calibers could be a big deal. One optic that you can dial in for each caliber, instead of an optic on 4 different rifles ($$$). Splurge once on a really nice trigger, nice grip, nice stock, etc. At any rate, these sorts of modular systems have been proving popular and I’m sure we’ll continue to see more of them.

    • The “bugs in 7.62×39” have already been worked out. Properly polished/enlarged M4-style feed ramps are just about standard these days, and C-Products mags run like a champ (10rd, 20rd, 28rd). I have a Bear Creek Arsenal 7.62×39 upper on a Palmetto State Armory lower. Zero hiccups with Brown Bear HP, Prvi FMJ, and Hornady SST.

      • I don’t consider the requirement to use one particular manufacturer’s mags to be “worked out”. It is a compromise at best and wouldn’t be considered acceptable in any other scenario.

    • D’oh! I thought the $2971 figure was for the base rifle with one caliber. For a full set of 4 caliber conversions (5.56, .300, 7.62X39 and 9MM) plus magwells for each, and what appears to be a Pelican case with custom fit foam, that’s actually pretty decent. And if it streets around or below $2500…. hmmmmmmm.

      Might have to put off the MDR for a while.

    • One lower, one upper, 4 barrels, 3 bolt carriers, 3 magwells, a really nice case, you’re looking at a complete rifle and easily $1000 in accessories here, so the MSRP doesn’t seem too wacky. Street will probably be under $2500 anyway.

      It’s not too bad if you’re actually using all of that.

  3. Nifty from a design standpoint (if it works).

    But if your family needs 4 rifles it doesn’t need one rifle plus a pile of unusable spare parts. For the price you could but 4 ARs.

    • Yeah, my thoughts. Maybe they will sell “extra lowers” and uppers being a custom design they have no compitition. So you can expect to paaaayyyyyyyyy…..

    • If it ends up costing more than 4 rifles…or even 3, I will just get 4 rifles instead…even if I had won the lottery the other day.

    • thats a good way of putting it, i was trying to justify buying this weapon system i’m no rockafella by any means

    • thats a good way of putting it, i was trying to justify buying this weapon system i’m no rockafella by any means

    • My buddy has a Hydra, and this seems to be a license copy of it or a knockoff thereof. It actually seems like a very good system overall except a few minor caveats.


      Agreed on the “10” platform version. I wouldn’t care as much about a lower, but an upper would be nice.

      • It would appear that they’ve licensed the design. MSRP for the full kit is a few hundred bucks less. I don’t [yet] know what parts they’re manufacturing themselves. If it’s some of the more important components, people certainly have brand loyalties one way or the other. I’ve never actually played with a Windham myself, but they have a good reputation.

        • I can tell you that my buddy’s receivers have Cerro markings on them so if they’re doing anything it’s likely final machining. Where I really think that the system falls short at some level is there aren’t really any options for hand guards; If they become more common that could change which would be cool.

          Another thing I don’t like about this particular kit is that the mag and mag well are for the Uzi style 9mm mags; my buddy has the Glock mag one, and I think that for people who are inclined to buy a kit like this it would be a better option.

  4. As a note:

    This is the same system that MGI makes that Nick reviewed a few years ago. They licensed it out to WW.

    I’m looking at building one to be able to pack on my motorcycle since my regular upper is too long to fit in the bags I don’t like strapping it across the seat because I’m afraid of it sliding out and taking an independent journey on the highway. The problem I had was that the kid behind the counter at one of the LGS I went to was too lazy to help me order one.

    What I like about it is:
    -You have ONE trigger feel for all your calibers (once you replace the mil-spec one that Nick hated so much).
    -The packability I mentioned.
    -You will save a little money come the end of the day due to the trigger/grip/stock being reused.
    -You only need to convince your significant other to let you get one rifle, the rest is just accessories.

    What I would like to do is mill down the side rails to flat, and depending on the internal structure of the forend, convert it to m-lok. Because I don’t use rails, but if I wanted I could put a small rail section on.

    • The one thing I will say about this gun is that the trigger is not terrible for a “rack style” AR trigger. It definitely feels like it was “tuned up” a bit versus just a standard CMMG parts kit trigger. I am sure it’s not Timney either, but the closest thing I have for actual reference is a National Match trigger which didn’t seem like an absurdly huge improvement.

      • I can’t say I’m a trigger snob like the rest of the reviewers are. The only AR trigger I have experience with is my stock trigger I put in my first build, which happened to be Windham Weaponry. It works well enough for me, but I haven’t had a chance to use mine past 80-100 yards. I’m not sure how it compares to any others to be 100% honest.

      • I’ve got no beef with the CMMG single stage parts kit trigger. Polish up the working surfaces and it’s really not bad.

  5. I don’t see any sights in the pictures.

    You can buy sights or optics, but since each caliber has a different trajectory you’ll need to re-zero every time you swap calibers. I guess you could buy a different front sight for each barrel if you don’t mind the dollars.

    So, rather than having 4 rifles, you have one rifle for the same money. And choosing a caliber means swapping parts and readjusting sights, rather than just grabbing the rifle you want.

    I don’t see utility or economy here. I only see novelty.

    • No problem, you just need to ballistically match all your 5.56/7.62/.300/9mm handloads so they all shoot exactly the same point of aim.

      Easy peasey.

      • In theory there is no difference between theory and practice; in practice there is.

        I reality, a 3,000 fps bullet is not going to match the trajectory of a 1,000 fps bullet.

  6. Ditch the chunky handguard and gas block and this thing would sell.

    I hate how many innovative companies like this seem to be way behind the curve as far as what is currently popular in the AR market.

  7. Most interesting feature is the detachable magazine well. You just cut what legally counts as the “receiver” in half. What would an 80% of that half-receiver look like?

  8. Heads up the magwells are $275 each from MGI. To use the 7.62×39 magwell which takes AK mags requires the right upper and BCG, the upper has to be wide enough for the AK mag to fit. But the magwell uses the AR mag release button to drop the mag.

    Trigger spring will have to be strong enough to smack cheap steel case primers.

    But on the other side you could use the trigger part of the lower to make a SBR in 9mm, 5,56, .300 and 7.62×39 or any other round that uses an AR-15 type lower.

  9. Is the 7.62X39 bolt proprietary, and hopefully bigger than the AR-15 bolt? I know that hogging out a 5.56 bolt so it can just barely extract 7.62X39 tends not to be good for long term usage and durability, vs something like what CMMG opted for: a proprietary AR-10 based bolt for their Mutant offering for long term durability and reliable extraction.

  10. Also: Glock small and large frame magazine wells and 10MM and .45/460 Rowland barrels, plz. 😀

  11. What I like about this product is the option it creates for us the consumer.
    If you like it, buy it. If there are flaws, don’t.
    If you think it’s good, but could be better, make it.

    Y – you
    A – always
    H – have
    O – other
    O – options

  12. not really very innovative. now when someone is able to make a quick swap between a 556 and .308, THAT will be amazing. but i just cant imagine that coming anytime soon. that would require some real innovation. unless i missed something

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