Rheinmetall Machine Gun 7.62
The German company Rheinmetall is currently in the process of designing a new machine gun that neatly solves the barrel overheating problem. Instead of one barrel, like most machine guns, the RMG 7.62 has three.
Despite the multiple barrels, this is not a Gatling machine gun, it is derived from another famous German model, the MG42. Unlike its predecessors however, the RMG is not meant to be a general purpose machine gun (GPMG). It is designed to be a vehicle mounted and remote controlled weapon that will provide greater range, fire control and safety than its counterparts.
Continuous Full Auto
The basis of the new machine gun is the well known MG3, a lighter variant of the WW2 legend MG42. The MG3 is a recoil operated, belt fed machine gun with a typically German roller locked bolt mechanism. Unlike the MG42, the MG3 has two theoretical firing speeds: 700-800 and 1.100-1.200 rpm, instead of the “insane” 1.200-1.500 rpm the MG42 used. Both models had a quickly replaceable barrel.
The new thing with the RMG model are three barrels bundled together, looking at first glance like a Gatling model. Additional barrels are there to ensure rapid barrel replacement when one barrel reaches critical temperature. This, of course, requires the presence of a thermometer and a servo engine which would rotate the barrels. This way, while the overheated barrel is cooling down, firing can continue without problems. When the second barrel overheats, it is replaced by the next one and so on. This system also reduces the wear-and-tear of the barrel, significantly increasing their life-cycle and reducing the chance of damage.
One of the advantages of the automatic barrel replacement is increased safety of soldiers during the exchange of fire. Previously, vehicle crews had to actually leave the vehicle to replace the barrel, which put them in significant danger from enemy counter-fire. Remotely controlled machine guns promise to put an end to that and allow soldiers to remain in cover/vehicle during the entirety of the engagement.
A Different Solution
While this system of three-barrelled machine gun has not been used before, there are examples that support the idea that long burst fire is a problem that has been solved a while ago, in a much simpler fashion, perhaps even a better one.
The first and the simplest solution is the installation of a heavy barrel. Thickness of a barrel in machine guns like M60 or FN MAG is larger compared to, for example, PKM, which means that it can theoretically fire longer bursts without overheating. On the other hand, that makes the whole machine gun heavier. Another solution is the use of ribbed barrels, which increases the barrel surface area and improves cooling. Finally, there is water cooling, which is also the first solution developed to solve the overheating problem. Of course, additional cooling water increases the weight of a machine gun even more.
All in all, the solution developed by Rheinmetall is certainly an interesting one, time will tell if it’s the best one.