MP 40 Bolt Replacement Issue

[Rekraps]

So I own a very nice C&R, all original parts (numbered) throughout the gun. Being paranoid about possibly breaking the matching firing pin, and possibly damaging the bolt (although I don't see how this could happen) I purchased an unmarked bolt, and buffer/recoil tube. Once installed I took a trip to the range and the gun works... sorta. A few light strikes, failure to extracts and I'm not happy. 

Has to be an issue with the parts, so I went home and disassembled the gun. Everything looks okay. But when I looked closely, very closely, two things became immediately apparent:

1. The firing pin, in its most forward position did not protrude through the replacement bolt face as far as when using the OEM bolt... maybe this caused the light strikes, and 
2. The extractor for some reason was depressed far enough to prevent the casing rim from engaging, thus it would not extract. I inserted a replacement extractor and it fit much better.

So, I then separated the two components, (recoil tube/replacement bolt) and inserted the spare recoil tube into the OEM bolt and sure enough, the firing pin protruded in what appeared to be an identical fashion as that of the OEM set-up. I then used the OEM recoil tube into the unmarked bolt and sure enough, the firing pin did not protrude as far as through the OEM bolt.

Conclusion:

My replacement bolt (obviously not OEM German) has slightly different dimensions that that of the OEM matching bolt and that slight different is sufficient to prevent the firing pin from protruding far enough to fire the round. 

All this being said, does anyone out there have a spare MP40 bolt (stripped okay) they would be willing to part with?

 

 

[TSMGguy]

MP40s were originally assembled by single highly trained individuals. There were parts and fitting variations. The parts interchangeability and uniformity found in American WWII arms did not exist. We occasionally see this demonstrated today.

 

I never replaced any of the original parts on my matching MP-40 in an effort to save them from wear and tear. It performs perfectly. I keep the gun in nice shape by not shooting it much. I don't take it to machinegun shoots.

 

My thought is that once separated, the original parts might never find their way back onto the gun if anything happens to me. The one part that cannot be replaced is the receiver, and it's subject to wear either way.

[Mad Machinist]

I have noticed the firing pins from D-K Productions have excessive protrusion from an original bolt allowing them to be fitted......I have one.....be happy to fit it to your bolt and buffer if you would like me to.

[Rekraps]

On 10/31/2022 at 8:06 PM, Mad Machinist said:

I have noticed the firing pins from D-K Productions have excessive protrusion from an original bolt allowing them to be fitted......I have one.....be happy to fit it to your bolt and buffer if you would like me to.

Very kind of you! 
 

Please send me a text (404.290.2911) and let me know what you would charge to do so! 

[azboater]

I also shoot an original German non matching bolt and firing pin in my all numbers and parts matching vet bring back FXO-41 MP-40

and it runs Flawlessly 

But before I paid the price for those,  I had a Portuguese bolt that absolutely would not work in my gun

and ended up selling it.

 

 

[Mad Machinist]

On 11/2/2022 at 5:53 PM, Rekraps said:

Very kind of you! 
 

Please send me a text (404.290.2911) and let me know what you would charge to do so! 

will try and give you a shout from the shop tomorrow....I see the 404...are you near Atlanta? I'm in Macon.

[Rekraps]

18 hours ago, Mad Machinist said:

will try and give you a shout from the shop tomorrow....I see the 404...are you near Atlanta? I'm in Macon.

Yep! Marietta. Leave me a VM or text and I'll call you back.