MP40 Bolt Armor Replacement? Opinions please

[fishermankw]

Was offered this bolt, told it was most likely an armorer replacement. Waffenamt with no serial number. The charging handle is evidentially snug, but also has the hex plate looking piece as an anchor, is this original? Thank you for the opinions and info, know just enough to be dangerous to myself.

 

[biggymu]

The cocking handle was peened in place inside the bolt like a rivet. It is not uncommon for them come loose over time and people tighten them up with a punch. The picture is not very clear but this appears to have been done to yours. Attached is an auction photo of an unmolested example. I don’t know about the armorers replacement aspect. This doesn’t hurt the functionality if the price is right.

 

[fishermankw]

Appreciate the feedback, that is a hat I thought as the others I’ve seen/had have been flush like the one pictured. I assumed it was something post war to tighten it. Just looking for a spare to shoot with so I can leave my matching bolt alone. The “patch” shouldn’t affect functionality at all I was told, correct?

 

[biggymu]

Correct. My shooter bolt handle was loose and I punched it tight. I have thousands of rounds through it. No issues.

 

[tsmgguy]

Right, there were two original methods of securing the drop safety to the bolt, crimping and welding. Welds didn't tend to later loosen up and require peening. If the crimped portion of this one protrudes into the bolt cavity, then an original recoil spring housing may no longer fit.

The large hole in the bolt opposite a crimp must have made it easy to remove original early hook-type cocking handles for replacement with drop safeties. This action was directed in early 1942.

The drop safety on my own all matching bnz 41 MP40 is welded in with the weld neatly dressed, as in biggymu's photo.

 

[Hambone]

Was offered this bolt, told it was most likely an armorer replacement. Waffenamt with no serial number. The charging handle is evidentially snug, but also has the hex plate looking piece as an anchor, is this original? Thank you for the opinions and info, know just enough to be dangerous to myself.

The potential issue with that repair is how the recoil tube / FP assy. will ride in there. Looks like a nut sticking out proud and will it scrape, beat, and jam against the top tube section of the recoil assy? They are flush in there for a reason. If the recoil assy has enough play inside that bolt to wobble around that protruding nut, is that more problems? May want to check that first.

 

[fishermankw]

The potential issue with that repair is how the recoil tube / FP assy. will ride in there. Looks like a nut sticking out proud and will it scrape, beat, and jam against the top tube section of the recoil assy? They are flush in there for a reason. If the recoil assy has enough play inside that bolt to wobble around that protruding nut, is that more problems? May want to check that first.

That was exactly what my concern/thought was. I’ve had a few dealings with him and said if there are any issues he’ll swap it out. I don’t know if it’s up 1/32 of an inch or 1/4 of an inch. Figured try putting a spring in, see if it catches or wobbles… or do you think it makes sense just to write it off and look for another?

 

[Hambone]

That was exactly what my concern/thought was. I’ve had a few dealings with him and said if there are any issues he’ll swap it out. I don’t know if it’s up 1/32 of an inch or 1/4 of an inch. Figured try putting a spring in, see if it catches or wobbles… or do you think it makes sense just to write it off and look for another?

At a minimum it's going to protrude into an area where no such protrusions should be. There's a little excess tolerance in there to stop binding, etc., but we're talking about an area that is going to be slamming and jumping and janking around under FA fire, alot. At a minimum that nut is going to be scraping against the bolt and could cause binding. Hand function is different than fire functioning. In short, might it run? Yep, never tried it. Would I run it like that? Nope. Can it be repaired properly with a weld and polishing? Sure, no problem for someone with reasonable skills.

 

[Hambone]

You know, in looking at it again close, it looks like someone just peened it with punches. I've done that. It may look more protruding than it is. A dremel zip could knock that down. I'm going to go with do it if the price is right. Not a hard fix, if it even needs it.

Edit: Fisherman, that's not a hex plate on there, that's four punches / peens.

 

[fishermankw]

You know, in looking at it again close, it looks like someone just peened it with punches. I've done that. It may look more protruding than it is. A dremel zip could knock that down. I'm going to go with do it if the price is right. Not a hard fix, if it even needs it.

Edit: Fisherman, that's not a hex plate on there, that's four punches / peens.

Thanks for the help/info, I think it was maybe just a bad angle that he took the pictures then. I think the deal/trade he offered is fair enough so I’ll probably go for it then. Be an easy fix if necessary and good enough for a shooter bolt it sounds like. I appreciate the insight, I know enough to be dangerous.

 

[fishermankw]

You know, in looking at it again close, it looks like someone just peened it with punches. I've done that. It may look more protruding than it is. A dremel zip could knock that down. I'm going to go with do it if the price is right. Not a hard fix, if it even needs it.

Edit: Fisherman, that's not a hex plate on there, that's four punches / peens.

Bolt came in today and it was peened, very slight raise. What I did find interesting was one of my spare firing pin assemblies fit and the other did not.

A separate question, this pin is in, but falls out if flipped upside down (though doesn’t completely fall out) how big of a deal would it be to just leave it alone? I don’t imagine it would be a costly fix if need be.

 

[Hambone]

I’ve had to do that exact peen repair on loose handles. When a handle gets loose it’s like a loose tooth….it’s coming out.

Leave that repair alone and run it. See what happens. Probably will run fine. Probably will smooth itself out. If it grates against the tube too much perhaps try flattening it a bit by peening it, being careful not to “undo” what was done by the punches. There’s usually enough tolerance slop necessary for those parts not to bind to allow that. Also, the MP.40 is pretty known for non-interchangeability of all parts without some hand fitting. Some parts simply won’t interchange at all, such as recoil tube sections and threaded FP/buffer assemblies.

 

[biggymu]

Regarding the second question:
The pin on the safety holding the detent ball and spring is falling out Ham ( look to the right and below handle). It needs to be held in place and the top of the pin punched like a rivet. Certainly repairable but seller should have disclosed this.
The whole safety cap will fall apart if not repaired. Kits to repair this used to be available.
Haven’t seen one in a while.

 

[fishermankw]

I’ve had to do that exact peen repair on loose handles. When a handle gets loose it’s like a loose tooth….it’s coming out.

Leave that repair alone and run it. See what happens. Probably will run fine. Probably will smooth itself out. If it grates against the tube too much perhaps try flattening it a bit by peening it, being careful not to “undo” what was done by the punches. There’s usually enough tolerance slop necessary for those parts not to bind to allow that. Also, the MP.40 is pretty known for non-interchangeability of all parts without some hand fitting. Some parts simply won’t interchange at all, such as recoil tube sections and threaded FP/buffer assemblies.

I’d heard some of them weren’t one for one but had assumed the assemblies would’ve been pretty easy swaps. Glad I hoard some parts ha.

 

[fishermankw]

Regarding the second question:
The pin on the safety holding the detent ball and spring is falling out Ham ( look to the right and below handle). It needs to be held in place and the top of the pin punched like a rivet. Certainly repairable but seller should have disclosed this.
The whole safety cap will fall apart if not repaired. Kits to repair this used to be available.
Haven’t seen one in a while.View attachment 377253

Talked with John Adamanski up in NH, he said it’s an easy fix for him. Have another one coming in that needs a little fix too probably send them both up to him and see what happens.

 

[Hambone]

That’s an easy repair. If you’ve got the proper punches, a mini anvil on the back of your vise, you’re good to go. I learned long ago how to do all this to keep my sewing machines running smooth I do use roll pins for that app and others but a firearm quality roll pin is usually too hard to peen. But, the softer solid pins sometimes lose their peen. I have shooters and shooter parts I work with and experiment with. I run FPB bolts and recoil systems, which can be tricky, but if you know what you’re doing you can make them reliable. Beats breaking a $100 pin or extractor. Keep us posted.

 

[Resmg68]

Hi guys, this thread is good and has been quite helpful, I just wanted to ask also if anyone has a exact idea of how to actually peen a new cocking post to a bolt? Like a way to physically support the bolt itself as well as the post? Perhaps with a photograph. I have a vice etc and punches, but it appears that one needs several hands.