I thought some of you would enjoy some pictures of a rarely seen German aircraft machine gun, the 13mm MG-131. This example was made by Heinrich Krieghoff Wafenfabrik, Suhl, Thüringen ('fzs'). The gun is here in the USA, a C&R registered fully transferable item, it is a "live" gun and is in (almost) shootable condition with only a very small amount of work short of being totally operable. It is in truly pristine, museum-grade, condition as you can see.
Originally a cowl gun, from likely either a Bf-109 or FW-190, a super rare flex gun pistol grip firing assembly complete with ratchet charging assembly has been located for it additionally. The flex guns were used on a multitude of defensive installations in concert with MG-81/81Z complements after retirement of the originally installed MG-15's.
MG131's are not really common but are by no means ultra rare. I've seen quite a few in the US with most being fixed guns like that pictured. I do know of at least 4 flex guns with pistol grips in private hands.
A good friend has a very nice condition flex gun that was at the SAR show in Phoenix last year along with 2 fully functional MG151/20's (I've fired them). A big problem with the MG131 is that no one used them after the war to any extent where the 151's were used in 20mm by the south african's and others up to the current time. The 13.2mm round used in the 131 is not common and was electric primed making ground gun conversions difficult. This makes the guns hard to shoot as the ammo supply is the real rare part. For some die hards finding the brass isn't a big deal as it can be made but electric primers are a problem. I've heard there were percussion primed/fired guns out there but all I've seen have been electric. Looking into the mechanism of the guns makes it pretty clear that adapting an electric gun to percussion would be pretty tough. For the shooters that makes the guns pretty useless and for that reason they don't seem to pop up very often. When they do the price is usually fairly low unless it is a truly gem quality piece. Being aircraft guns they are a bit of a niche piece for the collectors as well. Its sad in a way because the aircraft guns were a class all their own. Usually better quality and the designs were unique. The German aircraft guns remind me of the old world quality lugers and broomhandle mausers with their finely fitted parts and intricate machinework. The MG131 is a true example of that quality and a wonderful piece on its own. I've seen that remington was making an electric primed bolt action rifle called the etronx. I guess the idea was to have zero lock time or thereabouts. Not sure how successful the guns are but the electric primers are available and might be a good way of getting these 131's out in the mainstream and shooting again.
Frank, all of the Japanese clones of the 131 were percussion primed, evidently either the Japs were not up to the technology of the electric priming system, or their requirements didn't suffer from using percussion primed ammunition. Either way, there are adaptable percussion primed parts out there, i.e., the bolt. And, since the searing is the exact same physical location and method for either version, if one had a spare German bolt it could be modified to the Japanese version with some considered effort.
I would argue that the ammunition situation can be broken down into three problems, to me the least of which is the primer situation as, as you point out, if you are free to go with newly manufactured cases (expensive, but certainly do-able as the complete TDP for the 13mm ammunition is around) you can spec the priming for the most likely substitute that is readily available and closest match, electric 20mm Vulcan primers. And you would want to remake the new brass with a differing case neck spec as the original 13mm German cases are really built more like small cannon cases, more than enlarged rifle cases like the .50 BMG case is for example.
From there your next problem is re-wiring the control electrics for the much more energetic firing impulse required for the Vulcan primers(and at a really weird Hertz). So, an new firing circuit is required, again, do-able.
The next issue is that there are really no projectiles to use. Original projos were all "non-sporting" to say the least so importing even the AP ones would not happen and most quite simply were explosive. New projos would have to be made or possibly, adapted. Complete new projos is probably the way to go.
The other option is more arcane; the one avenue that I have been vigorously investigating is simply converting the gun to a new, more modern cartridge, in this case a modification of Cal. .50 M8 spotting rifle cartridge as the interior ballistics are insanely similar it turns out anyway. There are the same issues with primers, but not unsolvable for the M8 short .50 case. In going this route there is another ugly issue to raise its head, that of suitable links and adapting the feed cam pitch for them and for use of the new case and required links. I have gotten most of the leg wok done toward this end and all looks solvable, to me the ability to use common nearly off-the-shelf ammo components is worth the other headache of adapting to the new cartridge. Lastly, the current plugged barrel can be successfully salvaged- sleeved, and re-chambered for the M8 round.
And I'd still argue that less than 20-30 of any gun like this makes it "rare". ;-0 Having "4" of something is not in abundance, Ya know!
The gun is in the hands of an advanced collector who kindly provided the pictures to me.
-TomH
(Frank, talk with me in Casper tomorrow about this)
Sorry Tom,
Not trying to tear down your post or pictures by any means....definitely a super neat gun. I keep forgetting its you too and yes we can talk friday. Chuck and I got here wed afternoon so we are pretty much set up. I did bring the MG15 too and even loaded some mags....what a pain. I do have some ideas on the priming and links too. I'd really like to see one of these babies running again. The 151's are fun to shoot and excellent mechanically too. Mauser had some excellent engineers and machinists. See ya tomorrow.....
