7.62mm MG3 + Two More Barrels + Motor = Rheinmetall Defence RMG 7.62

Rheinmetall Defence are developing a new 7.62mm medium machine gun called the RMG 7.62 which takes a unique approach to dealing with heat, the age-old machine gun nemesis. At first glance it looks like a small version of the M134 Minigun, but the RMG is no Minigun. Unlike the Minigun, with its insane rate of fire, the RMG is designed to fire at the relatively slow pace of 800 rounds per minute (the exact rate of fire is user adjustable). What it lacks in speed it makes up for in endurance. When its barrel gets over heated the electronics rotate the barrels, replacing the hot barrel for a cool one.


The three barrel system would obviously be unpractical for soldiers on the ground, but it is perfect for use with remotely controlled gun mounts where it is neither possible nor safe for the operator to swap barrels manually. This setup would allow the remote-controlled gun to fire a lot more rounds and take fewer breaks than would be possible with a conventional single-barrel machine gun like the MG3.

The short clip shows a prototype RMG 762 firing but does not show the barrel changing procedure …

Many thanks to Kirill for the tip.

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.


  • Whoa! talk about bringing the heavy!

  • TLW

    This is actually a brilliant idea.

    • Max Popenker

      It’s an old idea, actually
      Americans tried similar concept (minus electronically controlled automatic barrel cluster rotation) back in early 1970s, when searched for new tank MG to replace ill-famed M73
      I believe it was described in the 5th volume of the excellent Chinn’s book “Machine gun”

  • rjackparis

    Eh. just strikes me as more things to go wrong. How much more complex would a updated actively cooled machine gun be?

  • Big Daddy

    Why not just have a heavy barrel and use a water jacket like the old water cooled MMGs of WWI? I think that would be a much better solution. Have a simple chain gun type motor driven bolt and a heavy barrel in a water jacket. You can fire all day long. Use a closed coolant system. if the system breaks down you can fire it like a normal gun. Firing form an open bolt it would cool very quickly between bursts and it would take a long time to get really hot.

    • Steve (TFB Editor)

      This is a simple upgrade over standard MG3. Water cooling would be big and bulky, requires a pump, radiator water pipes, o-rings etc.

      http://books.google.com/books?id=izGOfMdSm2IC&pg=PA133&lpg=PA133&dq=water+cooled+machine+guns#v=onepage&q=water cooled machine guns&f=false

      Although you can use them to make coffee 🙂

      • Big Daddy

        Using modern materials I can’t see it being very heavy at all. A simple pump running off the vehicle power which would be used to run the motor of the chain gun. The tube itself doesn’t have to be as thick as the Maxim one was. Also since the design is from scratch the coolant could possibly be run through the trunnion, add a small blower or pump to blow cool air into the breech after each burst. Each burst should not be too long, you’ll run out of ammo.

        Maybe this would add 10 pounds at the most and the weight would not be an issue since this design is for vehicles. I was a cav scout on M113s so I know a bit about light armor, not a lot but enough. I think it would be a less complex and less costly solution than adding 2 more barrels and some type of way to rotate the barrels off the gas or by using a motor. If you use a motor you might as well make the motor drive everything including the bolt. How about the complexity of a system using senors to tell it to rotate the barrels, sounds complex to me.

        Remember this is for vehicles which do not have as many weight restrictions. That type of mount takes M2s which would be much heavier than what I am talking about.

        The latest Russian GPMG the Pecheneg doesn’t have a quick change barrel. It uses a forced air cooling system. How good that works I have no idea. But at least they are trying something. Modern technology should dictate that a small lightweight cooling system could be made to retro fit a MAG or M240, MG3, M60 and so on, maybe even a M2.

        • themastermason

          I agree and suggest using different coolants and maintaining a heavy barrel just in case the pump system fails and the gun needs to be operated anyway.

        • foxtrot unicorn

          That makes sense – if the barrel is finned with a shroud, you could use the action to pump air through the heat exchanger.

      • Max Popenker

        Steve, why you mention MG3?
        Other sources mention RMG-50 as a parent design…

        • J.T.

          Look at the CAD design. That is pretty clearly a MG3 top cover, not one from a RMG-50.

      • Hunter57dor

        oh no, such complex systems. where would we ever find a simple system for cooling down a large block of metal with coolant…..

  • What ever happened to the Gast Gun?

    • Eric S

      Probably the same thing that happened to the Ripper Gun. It didn’t fill a need at a specific time.

      • Uberyeti

        It was a good aircraft cannon – at least the Soviets thought so.

        Think about it – you can get 3000 RPM from a gun with only one third as many barrels as the Vulcan. It’s light, reliable, and simple. I am also surprised they are not in wider use.

    • dp

      Yes, exactly… and here we go!

  • The Germans had the same problem in WW2…always over engineering their weapons. Their tanks were engineering marvels and were so complicated to produce that mass production was never achieved and when a tank broke down it took alot of time to return them to service. This weapon appears to follow the same pattern. It seems to be well engineered and I’m sure it took alot of intelligence to design and build this thing…but what will that translate to on the battlefield?

    • NorThor

      well its a sollution to the simple fact that you can’t change barrels on an MG3 when its mounted in a RCWS or COAX. It’s that simple.

      The MG3 is a brilliant piece of equipment. Its simple to use, packs more punch than any other conventional GPMG out there and troops in general are very familiar with it. Its very unpractical for a RCWS though due to its massive heat buildup that demands regular barrel changes. In an infantry squad (norwegian army) like the one I was in, the MG fireteam spotter would carry several spare ones and the drill to change barrels was very simple and fast (just 6-7 seconds, faster if you drilled enough).

      • I understand that it’s a solution…my only concern is wether or not this thing is too complicated to be easily serviced or reliable?

  • Lolinski

    Its a game changer! Nevah been dun befo’.

    It does look cool though.

  • Gidge

    Has anyone thought of just using heavy barrels with integral heat sincs? It’s not that big a deal to mil fins into an oversized barrel

  • bbmg

    As mentioned below the Russians as usual seem to have come up with a simpler more elegant solution for their Pecheneg: http://www.youtube.com/watch?v=O6TmuOHg8yk

    The “forced air” system is essentially copied from the Lewis gun, one would think that modern design techniques and materials applied to the idea would result in a much less complex weapon which would be similarly effective.

    Once comparison I would like to see would be to make a single finned heavy barrel of the equivalent weight of the three barrels and rotating mechanism and see what sort of rate of fire you could get from that.

    • Kirill

      The PKPs barrel, while efficient as it is, is not nearly as good as this particular system. The heat dispersal rate in the PKP is significantly higher than in previous versions of the PK Machine Guns, but it still heats rather fast when you send several hundred rounds downrange. It is an offensive weapon, make no mistake. It CAN be used for static defense, but it typically is employed as a offensive weapon.

      As for this aystem, it proves to me much better than a water jacket due to the fact that each of these barrels can take higher heat capacity than a normal barrel (Like the MG-3), and have three of them rotate. They aren’t going in a mobile position, they will spend much of their time static.

    • dp

      I basically agree with you (as well as with Kiril further down). You are each looking at an talking of distinctly different applications. Every solution is compromise in a way and you cannot avoid that.

      While emplacement guns should do well with thick, possibly finned (such as Japanese model 97) and heavy barrel, they can (granted conservative regime of fire) achieve nearly thermal balance; I worked on this issue myself and would therefore endorse this approach. Water-jackets is way of past; too complicated.

      For mobile application, on the other hand, the Pecheneg is close to ideal solution. At this particular design the creators managed to obtain more effective cooling air draft in comparison with Lewis (whose ‘funnel’ was often removed). Also, worth of noticing is its stability during fire. Look closely at its detail; this is optimized for economical manufacture as well as function – very efficient design indeed. This is way ahead of any western gun.

      I also agree with those criticizing German approach as “over-engineered”. This is exercise of technical exhibitionism, more of toy than practical item. It appears highly technical, but it is scarcely practical solution. Taxpayer’s money “well spent”, if adopted to be sure.

    • snmp

      You could found the same way system of coolling the barrel with Italian SMG SITE SPECTRE M4 (HC Falcon Ranger …) . That ‘s the SMG of Will Smith (Spooner) in iRobot (Film, 2004)

  • WilliamC1

    Would this have any advantage over a three barrel Gatling-type gun set to fire at a more moderate rate of fire? Both need an electric motor. I suppose this uses some spare MG3 parts, but other than that would it really be much lighter?

  • Why not just have the barrels rotate Gatling-style? That would only give each barrel a sustained fire rate of 267 rpm and eliminate the potentially unreliable barrel temperature-sensing electronics.

    And going with the M134 feed system, it would practically eliminate jams by not using gases or blowback to cycle the action. Enters the chamber, firing pin strikes the primer, doesn’t fire? No sweat, just gets extracted and moves on to the next round.

    • dp

      Good way of looking at it! This is basically what Minigun does. Or, another approach might be twin-barreled gun with controlled rate of fire for each barrel by inter-imposed link. Something like Russian GSh-23 cannon (which on top of it is self-powered), but with lesser calibre. There is no need for new ‘inventions’.

      • dp

        Here is page on mentioned cannon. It is in foreign language but it has plenty of detailed images in it. It is based on Gast gun. I can imagine this being scaled down to suitable size.
        http://www.lietadla.com/vyzbroj/gs-23.htmThere is also GSh-6-23 which is full on Gatling type.

  • Cuban Pete

    I once got to put 200rds on a twin MG3 mount in a Spanish Navy vessel. WOW!!! Heck, DOUBLE-WOW!!! Made our pintle mounted M60’s look like a toy.

  • keith

    Why not just build heat sinks into the barrel shape/design?

  • snmp

    Russian have this sort minigun with 3 or 4 barrel like the GShG-7.62, YakB or the Slostin (selfpower) : http://4.bp.blogspot.com/-cA_i8oyUs2M/TnFbfWPM9sI/AAAAAAAAARg/6wXMQ4lSG1A/s1600/SlostinGun.jpg

  • if we’re not concerned with weight wouldn’t a larger barrel make sense? Or heavier materials? Ceramic composites perhaps? There’d still be the issue of breech erosion, would constant barrel swaps make enough of a difference to make the changer worthwhile?

  • whodywei

    Maybe it’s time to bring back the water cooled machine guns ???

    • Mazryonh

      Yeah, I’m surprised that vehicle-mounted machine guns don’t have a mechanism to run coolant through the gun and then through the vehicle’s radiator to cool it off. Water cooling for machine guns is late-19th century to early-20th century technology; adapting it to modern standards shouldn’t be difficult. It would also mean less moving parts, and would be ideal for vehicles like Humvees with CROWS modifications to allow the crew to fire the weapon without exposing anyone. After all, you can’t change barrels while inside a Humvee–might as well give the one barrel you’ve got a reliable cooling system.

  • Ian McCollum

    This type of system was used on the Lowell gun, a contemporary of the Gatling. It was fired by hand crank, and had 4 barrels. Unlike the Gatling, the barrels didn’t rotate with the firing mechanism – instead you would shoot through a single barrel until it got too hot, and then manually rotate the second barrel into position and continue firing.

  • thorsuth

    so it’s basically a slowfiring MG3 with a new barrellchange system. I get how this is a good system for RCWS use but you gotta admire the old system. In the norwegian army we were drilled to switch these things by hand, took us no longer than 7-8 seconds. Germans had guys who could do it in 3 seconds.

    • Uberyeti

      That can’t be done on a remote weapons mount like the one in the pictures, and it’s very difficult to do it on a manned pintle mount atop a vehicle.

  • Vermin.308Winchester

    what the hell happened to active cooling its like every company made an agreement to not develope that tecknology and instead sell emplament guns with air cooled barrels on smooth bering mounts that could handle the weight and swing buetifully

  • Secundius

    Does it perform like a “Gatling Gun” or does in perform like a “Auto Revolving Cylinder” action.