Bolt locking in barrel extension

Anything MG42 related.
Post Reply
bulletpc1
Hauptgefreiter
Hauptgefreiter
Posts: 5
Joined: Thu May 07, 2020 6:15 am
Anti-spam: Mg42
Location: NE Ohio

Bolt locking in barrel extension

Post by bulletpc1 » Fri May 08, 2020 12:53 pm

I recently was asked by my brother to solve a problem on his MG42 SA that he purchased years ago that was complete but unassembled. He had a local gunsmith look at it and had it for over 2years. I told him to get it from him and I would look at it. I don't have any experience with MG42s but from what I have seen on this forum I believe I know what the problem is. It's that I don't know what to do about it.
When charging the bolt to battery on an empty chamber the bolt gets locked into the barrel extension. It appears that when using the charging handle back the recuperator doesn't bring it back far enough for the cams to push the rollers out of lock up. When I push the barrel bearing from the front by hand it only goes .173" in before it won't go any farther. Is this a normal distance when pushed in by hand? I tried pushing the recuperator rod in about 1/2" using a large long screwdriver through the barrel door open. . It appears to me that the recuperator tension is what is why it won't go back far enough. Is there any way of fixing this other than replacing recuperator springs? The distance between the bolt head and barrel facing is around .02" as it should be. The charging handle is not bent and the rollers move easily in bolt head and move to the unlock position when pushing them in when placing the bolt in the barrel extension out of the gun by gently squeezing with my fingers. No burrs or damage to them. I've checked the archive posts and see this comes up occasionally but without any remedies. Any help would be appreciated.

User avatar
JBaum
Administrator
Administrator
Posts: 3078
Joined: Sat Mar 12, 2005 8:41 pm
Anti-spam: Mg42
Location: NE Ohio
Contact:

Re: Bolt locking in barrel extension

Post by JBaum » Fri May 08, 2020 3:26 pm

Good diagnosis work so far.

On a factory gun, the barrel recoils about 7 mm rearward before the rollers contact the cams to start unlocking, but it has to go further than that to finish unlocking. If it only moves .173" (equals 4.4 mm), there's the problem. You need to find what's causing that.

Will the barrel go further rearward with the bolt not locked to it? Take the bolt out of the gun and see if the barrel bushing goes in until it's flush with the muzzle threads. It should. You'll be compressing the recuperator springs when you do that. I suspect the barrel bushing won't go in that far with the bolt out of the gun. If it doesn't:

I'd say it's most likely to be an incorrectly assembled or defective recuperator. Two bolts hold the recuperator in place. Remove it from the gun. Then, make sure the front bolt is in the recuperator correctly. It can be put in backwards. The tail on the front bolt goes toward the rear.
See link: viewtopic.php?f=39&t=1612)

See if it works freely on a workbench. It must work freely for the gun to work properly. If it doesn't, take it apart and see what's going on with it, or replace it with a spare recuperator. Dipping it in kerosene and shaking any dirt out of it is a good thing to do at this point. Also, put a little oil in it and stand it up on end for a while to drain out the excess after assembly.

The MG42 repair manual shows how to make and use the tool for recuperator disassembly. Be sure to wear eye protection. The springs are strong and they like to fly.

Most "gunsmiths" have no idea what they're looking at or how an MG42 works. The guy probably looked at if for an hour (if that), realized he was in over his head, and put it away while he was waiting for the lightning bolt to strike him and give him the solution. Two years later, still no lightning.
John@German<remove this>Manuals.com

http://www.GermanManuals.com

bulletpc1
Hauptgefreiter
Hauptgefreiter
Posts: 5
Joined: Thu May 07, 2020 6:15 am
Anti-spam: Mg42
Location: NE Ohio

Re: Bolt locking in barrel extension

Post by bulletpc1 » Fri May 08, 2020 4:59 pm

JBaum, Thank you for your quick response. I tried what you said. This time instead of pushing by hand on the barrel bushing, I pushed it against my basement wall and it compressed the bushing with .276 left sticking out which is better but not flush as you stated. I think you are right about the recuperator incorrectly installed as when he first bought this gun he couldn't close the barrel door as the recuperator kept it from closing. The gunsmith ground the the corner of the barrel extension on the side of the recuperator enough to seat the barrel and close the door. It couldn't have been much. You can hardly tell. Here's the situation of him buying it. He bought it from someone in California on Gunbroker who claimed he had 2. The one he kept was complete and working. This one he sold my brother was complete but not put together. I told him he screwed up as this guy probably started with this one and screwed it up and sold it after assembled another one successfully. So the barrel bearing should be flush with the muzzle threads when completely compressed? It's .276 with the recuperator completely bottomed out.

User avatar
JBaum
Administrator
Administrator
Posts: 3078
Joined: Sat Mar 12, 2005 8:41 pm
Anti-spam: Mg42
Location: NE Ohio
Contact:

Re: Bolt locking in barrel extension

Post by JBaum » Fri May 08, 2020 7:18 pm

My original, full auto/never been cut MG42 barrel bushing goes in until it is flush even with the muzzle threads. Your barrel in only recoiling about half of what it should. That's either a recuperator problem, or the front barrel shroud is too short.

I suspected the same events with the seller as you. If it was finished but not assembled, why wasn't it assembled? That makes no sense, unless it didn't work.
John@German<remove this>Manuals.com

http://www.GermanManuals.com

bulletpc1
Hauptgefreiter
Hauptgefreiter
Posts: 5
Joined: Thu May 07, 2020 6:15 am
Anti-spam: Mg42
Location: NE Ohio

Re: Bolt locking in barrel extension

Post by bulletpc1 » Fri May 08, 2020 8:06 pm

John, I think you're right on about the front barrel shroud being short. My brother told me that was what the gunsmith thought who had his gun for 2 years. Thanks once again.

bulletpc1
Hauptgefreiter
Hauptgefreiter
Posts: 5
Joined: Thu May 07, 2020 6:15 am
Anti-spam: Mg42
Location: NE Ohio

Re: Bolt locking in barrel extension

Post by bulletpc1 » Sat May 09, 2020 7:56 am

John you were right. I measured the front barrel shroud and compared it to a post on mg42 dimensions on this site and it comes up .2265" short.
The post shows total length of 22.2" and his is 21.9735". I guess he's screwed as I don't think he would want to sink any more money into this project as it is only a semi auto. Changing out the front shroud with another one would be too cost effective. He'll have to settle for a wall hanger I guess unless there is another alternative that I'm not aware of. I need to ask my brother but I think he told me this was a Wiselite receiver and front shroud in the auction description. After searching the web I find lots of problems and complaints on Wiselite MG42s.
Last edited by bulletpc1 on Sat May 09, 2020 10:42 am, edited 1 time in total.

User avatar
JBaum
Administrator
Administrator
Posts: 3078
Joined: Sat Mar 12, 2005 8:41 pm
Anti-spam: Mg42
Location: NE Ohio
Contact:

Re: Bolt locking in barrel extension

Post by JBaum » Sat May 09, 2020 10:39 am

Yup, that would do it. Once it's the right length, you might need a new recuperator part since it was shortened to make it allow the barrel to fit.

The front shroud can be cut into two pieces, spread to the correct length, then tig welded back together. It's not that big of a deal, for the right guy.

I'd suggest contacting https://lewmanarmsmanufacturing.com/

They can fix it if they have the time.
John@German<remove this>Manuals.com

http://www.GermanManuals.com

bulletpc1
Hauptgefreiter
Hauptgefreiter
Posts: 5
Joined: Thu May 07, 2020 6:15 am
Anti-spam: Mg42
Location: NE Ohio

Re: Bolt locking in barrel extension

Post by bulletpc1 » Sat May 09, 2020 10:47 am

Thanks John- I'll pass that information to my brother as I think I've done all I can. I don't think you saw that I edited my last post that I'm pretty sure this is a Wiselite receiver and front shroud as when I got through editing I saw that you replied to my last post while I was editing.

User avatar
JBaum
Administrator
Administrator
Posts: 3078
Joined: Sat Mar 12, 2005 8:41 pm
Anti-spam: Mg42
Location: NE Ohio
Contact:

Re: Bolt locking in barrel extension

Post by JBaum » Sat May 09, 2020 6:54 pm

Nope, hadn't noticed that. Wiselite didn't have a good reputation.
John@German<remove this>Manuals.com

http://www.GermanManuals.com

Post Reply
  • Similar Topics
    Replies
    Views
    Last post
cron