Crack in MG 42 Receiver and stuck cases

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maxfaxdude
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Crack in MG 42 Receiver and stuck cases

Post by maxfaxdude »

I bought a C&R full-auto MG 42 about 1 year ago that I've put about of 600 rounds of 7.62 and 8 mm through. The gun has performed flawless until my lasting outing when cases got stuck in both the 7.62 and 8 mm barrels ending the fun for the day. The stuck cases in both barrels were very difficult to remove - I had to use an aluminum rod inserted into the muzzle end and pound the rod with a hammer to get the cases out. I gave the gun a thorough cleaning and noticed a small hairline crack on the left front part of the receiver that I know is new. The ammo I have been using is steel cased Romanian 8 mm and steel cased Russian 7.62. My question is what is the best way to repair the receiver crack and is it related to the cases getting stuck in the barrel?
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Re: Crack in MG 42 Receiver and stuck cases

Post by maxfaxdude »

Picture of the hairline crack in the receiver.
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Re: Crack in MG 42 Receiver and stuck cases

Post by amafrank »

There was no pic attached to the post. It will help considerably to give more detail on the the sticking cases and chances are that the crack has nothing to do with the sticking. It is quite possible that the crack has something to do with a recuperator that is worn out and needs new springs. You should contact Bob Naess at Black River Militaria for the repair of the crack and the recuperator if necessary. He has a lot of experience with the guns and is very knowledgable.

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Re: Crack in MG 42 Receiver and stuck cases

Post by JBaum »

As Frank said, Bob Naess is the man to take it to. I have to wonder though, why you'd buy a great gun and put steel cased ammo through it. Brass is a self lubricating metal. Steel is not. I wouldn't buy a BMW and syphon gas from the junk yard cars just to save a buck a gallon.

It wouldn't be a bad idea to get a large brass bore brush (.45-.50 caliber) and put it on the end of an electric drill, and use some bore solvent with it to clean the chambers. Could be a build-up of crud from the ammo.

How's the headspace? Have you tested the recuperator function? Are you using a heavy bolt with a standard buffer?
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Re: Crack in MG 42 Receiver and stuck cases

Post by amafrank »

As I said in the first post details will help a lot.

As for the steel cased ammo that is not the problem and isn't a problem for the gun. It was designed to use steel cased ammo from the start. Steel is much more consistent in operation and at the speed the gun runs will have much fewer issues. The idea that steel will damage your gun but running a brush on a drill with abrasive won't is silly. Polished chambers can sometimes be worse for case sticking than rough ones too so think twice about any sort of polishing compound.

Commercial brass cased ammo is frequently damaged in operation due to thinner case walls. Lubricity of the case has little to do with the operation of the gun and the laquered or otherwise coated steel cases are just as good as the brass for that aspect. We have run hundreds of thousands of rounds of the Romanian 8mm through all manner of machineguns including MG15s, MG34s, MG42s, MG81s (which run at 1800+ rpm) and a variety of watercooled guns like the Maxims and Browning types. Never have we had an ammunition related problem with any of the guns other than the occasional dud primer. I don't know about the russian ammo you're using in the 308 but if you're having problems with cases sticking in both cals its probably not the ammo.

Regarding damage due to the steel cases have a look at the fired cases and see if there is any exposed steel anywhere. With all the romanian we've fired we never see any steel, only the laquer. The laquer is softer than any type of brass ever made. What this means is that the only thing to touch any parts of your gun is the laquer so there will be no more wear than brass cases cause and likely it will be less. There seems to be a prejudice against the steel cased ammo that is completely based on emotion and not on research or fact. In the original work on the roller locking system by mauser the only ammo they used was steel case because it was consistent in its adhesion to the chamber walls under pressure while brass was not. It took much time and effort to make the CETME/HK roller locking guns work with brass consistently. Case material is not the problem with your gun and you should feel no qualms about running steel cased ammo in it.

There are chemical compounds that can create problems with chamber sticking. Mustard gas was a big problem in WWI and there are others which were not intended to kill everyone as well. There was a huge shipment of 7.62X54R from Hungary about 15 years ago that had some problems. It had some sort of coating that would cause the cases to start sticking after you'd run a few thousand rounds through the gun. It might have been a preservative or something resulting from the breakdown of other materials that were in storage with the ammo. It appears to have been activated by heat and the chamber of a firearm is actually the last place to heat up. Cleaning your chambers is a good idea but I'd go easy on the power equipment. I'd try cleaning some ammo as well and try it to see if the sticking continues. If not than maybe you have a contamination issue.

Headspace is rarely an issue with the MG42. If you don't have cases heads being ripped off than you're fine. It won't affect the case sticking issue so it won't help here. Chamber damage due to overpressure is more likely. You can use a borescope to have a look inside the chambers though a chamber cast will show better if there are any bulges. The thing that makes me wonder if its not chemical contamination is that it has happened to more than one barrel in more than one cal. This is unusual.....

Frank
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Re: Crack in MG 42 Receiver and stuck cases

Post by maxfaxdude »

Thank you guys for the replies!

Sorry for the delayed response. I was on vacation in BC, Canada with no internet.

Here's a picture of the receiver crack.
MG42 crack.pdf
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Re: Crack in MG 42 Receiver and stuck cases

Post by maxfaxdude »

I was using Hot Shot Romanian Ammo - the newly manufactured stuff (not the 1970s surplus in the green spam can).
b63bdf6f4501014adb5c154a47609675_1.jpg
Using this ammo, I had the same problem once with a case stuck in the chamber of my full-auto MG34. I've shot a couple thousand rounds of this stuff and occasionally get a dud. I did some internet research and some people were also having trouble with spent cases getting the chamber in 2014. One guy attributed it to the ammo being out of spec.

As for the guns, both my MG34 and 42 are in good shape. The recuperator on the 42 is fine, the chambers are very clean and nothing else seemed amiss. I'm thinking that it could be this particular lot of ammo I've got.
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Re: Crack in MG 42 Receiver and stuck cases

Post by hakentt »

That crack has nothing to do with malfunction of the gun, it is not on a critical location.

That Romanian ammunition is from 1973, look at the two digits. All hot-shot did is buy some garbage Romanian surplus and boxed it and called it their own brand. Any ammunition that is that old will be unreliable.
Try some new PPU or Igman full metal jacket 8mm
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