The MG34 Repair and Troubleshooting Thread

Well This just showed up :)

More rollers and firing pins...lol... and a bolt body to complete my 2nd BCG.

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Brian46 said:
308 conversion would be the way to go, how reliable is it?

I want a 1919 in 308
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I have 2 MG 34s one in 8mm and one in 308 ,,and the 308 runs a lot better than the 8mm ,,the 8mm runs fairly well though after 6 years of learning to fix it
the 1919 I have in 308 out does them all in reliability,,never has fails
 
Found another set of bolt rollers in the mail today :) and was able to make my FA bolt to SA as well this afternoon :)

Time to get my 2nd bolt together.

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Tomorrow I'm taking mine to the range. Hopefully it all goes well.

I'm watching what Dilligaf has to go through and I'm kind of skeptical about keeping this pig running. I'm not a machinist.
I ripped the rifle down and cleaned it and oiled it. One of the rollers seems stiff and doesn't turn easily.
Do you guys use grease or oil? I was thinking of using grease - I read these like to run wet.

I bought a Yugo belt loader and am waiting for it to come in.

Also 8mm ammo is not cheap - I will be saving my brass and reloading.

I'm apprehensive and excited - lol


For those using the 308 conversion do you use the 8mm mauser belts? How to they work?
 
If I read somewhere that the TNW rollers are reproductions and are to soft and will break.

And I can confirm this after what happen to mine. It will also break the bolt stop in the process.

As well the reproduction firing pin is way to strong and will break the firing pin.

the best part in all of this! North Sylva will tell you to pound sand when it comes to warrenty work. I love those guys and their honesty...lol...
 
Manners said:
Tomorrow I'm taking mine to the range. Hopefully it all goes well.

I'm watching what Dilligaf has to go through and I'm kind of skeptical about keeping this pig running. I'm not a machinist.
I ripped the rifle down and cleaned it and oiled it. One of the rollers seems stiff and doesn't turn easily.
Do you guys use grease or oil? I was thinking of using grease - I read these like to run wet.

I bought a Yugo belt loader and am waiting for it to come in.

Also 8mm ammo is not cheap - I will be saving my brass and reloading.

I'm apprehensive and excited - lol


For those using the 308 conversion do you use the 8mm mauser belts? How to they work?
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As a new MG34 owner this year myself. I have to say that I think the majority of failures and part breakages are caused by lack of “initialization’ of the MG34 before firing.

For example, you mentioned in your post that “one of the rollers seemed stiff”...if that’s a bolt roller, fix it before firing a shot or you will be replacing it and possibly the bolt stop. If it’s one of the 2 trigger bar rollers in the trigger group, check that they are free moving now and lubricate, or break parts and have to fix.

TNW recommends a specific lubricant TW-25 - I used Lubriplate grease from my M14 for a few outings and it was fine, but use the right lubricants or break your new (80-year-old) rifle. I ordered TW-25 from Amazon. You have to lubricate the bolt rollers, bolt itself, locking lugs, and camming surfaces at front of receiver and barrel extension.

Bottom line - get your MG34 right before firing, or break it and have to play fix-it.

The .308 conversion is amazing - beautiful barrel and not one feed issue on first range trip. The replacement feed pawl is simple to install with a punch, and feeds both 8mm and .308. My kit included a .308 belt, which I forgot on my first range trip with the .308, so I used a well oiled German belt that was a bit worn and it worked fine. Loading rounds in a used belt for .308 should take no more force than 8mm or else you may have problems stripping. I didn’t install the feed tray spacer but no feed issues with bipod/shoulder firing or firing from my MG3 Lafette mount.
 
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Hint on the bolt roller - use some CLP on the roller where the 2 rollers meet and at the outer ring of the roller - try to squeeze some lubricant so it gets into the roller, then chuck the roller into an electric drill and spin the roller, putting some gentle force in a circular motion using the drill like when you widen a drill hole. Do this for 30 seconds or so, and check for exceessive friction heat, and repeat. I did this on a recently installed bolt roller that was a bit sticky and it loosened right up after 5 mins of this process.
 
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DILLIGAF said:
If I read somewhere that the TNW rollers are reproductions and are to soft and will break.

And I can confirm this after what happen to mine. It will also break the bolt stop in the process.

As well the reproduction firing pin is way to strong and will break the firing pin.
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So buy new german rollers and a new firing firing pin spring?

Also good advice Firearms Enthusiast - I will try the drill trick. (Edited to add - The drill trick worked like a charm. Sprayed lube and spun the bolt roller in the drill chuck and now it rolls freely. I owe you a beer :) )


Thanks guys.
 
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Manners said:
So buy new german rollers and a new firing firing pin spring?

Also good advice Firearms Enthusiast - I will try the drill trick. (Edited to add - The drill trick worked like a charm. Sprayed lube and spun the bolt roller in the drill chuck and now it rolls freely. I owe you a beer :) )


Thanks guys.
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Great news! Bolt should slide smoothly in the receiver and lube the bolt. Check bolt rollers for incipient damage after firing 10-20 rounds and let us know how it goes at the range. Some fail to feed or eject is normal at first...after 100 rounds the parts work together much more smoothly.

Original German firing pin spring lightens the force required to cycle and recock the bolt but lowers firing pin force so may not fire surplus ammo reliably. I handload for 8mm and my spring fires CCI primers like clockwork.
 
A good grease to use is the super lube stuff that's available at Greggs distributing
I use it in my 34 and it works good
As was said above change out the tnw firing pin spring for an original one the gun will work much better
I took mine to the range the other day and a few guys commented on how well it ran. I had a few stoppages when I tried to bump fire it but ran flawless otherwise
 
From what I've seen here I wonder if these rebuilds/rants will ever fire well with the great 8mm reloaded surplus bs that is around?
 
So at the range shooting PPU new 8mm rounds. Two belts loaded and ready to go.

Fired of 30 rounds - each time there was a failure to eject and the bolt seemed to catch in mid cycle. You can't ride the bolt home on this gun you have to #### it back and then release it so it slams home. Otherwise the firing pin doesn't work. So one shot, then cycle bolt to eject and load a new round. I pulled the bolt after 10 rounds and relubed it - tons of lube.
I figure it's getting caught because of tension in the upper receiver door. It is tight and I can't slide the catch and flip it up and open after a shot - I have to cycle the bolt and then it frees it up. Pull upper door and strip it/lube it. Keep working on it and lubing it. Kinda frustrating.
10 more shots and the last 3 cycle good with each trigger pull. I'm thinking we're out of the woods....
The next trigger pull it fires and then goes full auto for 7 rounds. Range officer comes over and starts to give me hell. I am/was in control of the gun but it wasn't expected. I explain to RO that it's a new toy. I proof the gun and everything looks ok. Two rounds left in belt so I rack bolt back and the gun slam fires.
At that point I'm done so I pack up and leave the range...

I figure the firing pin is broken. I will strip it down later.
I'm unimpressed but got to fire an MG34 full auto which is something I guess :bangHead:
 
Manners said:
So at the range shooting PPU new 8mm rounds. Two belts loaded and ready to go.

Fired of 30 rounds - each time there was a failure to eject and the bolt seemed to catch in mid cycle. You can't ride the bolt home on this gun you have to #### it back and then release it so it slams home. Otherwise the firing pin doesn't work. So one shot, then cycle bolt to eject and load a new round. I pulled the bolt after 10 rounds and relubed it - tons of lube.
I figure it's getting caught because of tension in the upper receiver door. It is tight and I can't slide the catch and flip it up and open after a shot - I have to cycle the bolt and then it frees it up. Pull upper door and strip it/lube it. Keep working on it and lubing it. Kinda frustrating.
10 more shots and the last 3 cycle good with each trigger pull. I'm thinking we're out of the woods....
The next trigger pull it fires and then goes full auto for 7 rounds. Range officer comes over and starts to give me hell. I am/was in control of the gun but it wasn't expected. I explain to RO that it's a new toy. I proof the gun and everything looks ok. Two rounds left in belt so I rack bolt back and the gun slam fires.
At that point I'm done so I pack up and leave the range...

I figure the firing pin is broken. I will strip it down later.
I'm unimpressed but got to fire an MG34 full auto which is something I guess :bangHead:
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check your sear and sear ring. make sure your sear is flush with the bolt when its cocked.
 
Manners said:
I'm unimpressed but got to fire an MG34 full auto which is something I guess :bangHead:
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I was so impressed I might of loaded another 50 round drum to be sure it was acting up :) Mine did the exact same thing, The New firing pin spring binded and left the firing pin forward :) thus breaking the firing pin after a few drums...lol...

It took me about 100 rounds for mine to break in. And 250 rounds to break it...lol...

I get almost no stoppages ever since I use the belt loader to load my rounds, the Yugo belts from Marstar seem to also work better than the Original WW2 ones I have.
 
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The area i have circled in the picture could be coming into contact with the the trigger gate if it is not flush with the bolt when its rotated into the firing position. i have seen it before and it is exactly like you describe (the runaway gun part). I hope you get it figured out. good luck :cheers:

Im not sure why the picture rotated?..
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