What caused this bolt FAILURE?

[MauserMatt]

I had no other damage to the weapon itself.. Just a little scared when my barrel door popped open and I see this:



And this is the round:



And this is what I found when I pulled my bolt apart for cleaning:



Weird how nothing else is bent or anything.. Just that.. This is a Pirate bolt.. Probably about a year old or so.

Any help? I'd really like to shoot this thing again....

[JBaum]

Once you got the cartridge out of the chamber, did you check the chamber to make sure there wasn't anything stuck in it? A cartridge should fall into the chamber clear up to the extractor groove just by gravity, and fall out when you turn the barrel over.

[fjruple]

Matt--

Looking at your photos its a little tough to see all of the primer pocket of the cartridge case. It looks like a poorly manufactured Berdan primed case. Does the cartridge have the two flash holes in the back of the cartridge? If the two flash holes are not there and the primer is loaded into the casing. When the gun is in a locked position and with no flash holes in the cartridge case when stuck by the firing pin all of the primer gases will go into the firing hole and into the internal parts of your bolt and bend or break firing pins. That's my guess. I have seen this happen to at least two pistols in the pass three years. The culprit in both cases were no flash holes in the cartridge case (poor QA).

I lot folks in the shooting community underestimate the power of those little primers. In a very confined space, the build up of pressure could be pretty great.

My .02 cents

--fjruple

[Blanksguy]

MauserMatt,
Please give us a little more/detailed information on what you were using and exactly what happened so that we can help you sort this out.....and give you our ideas on what happened and "why"/and what to check.

From your posting, I understand that you were firing a semi-only SA42.....correct (?).

From what I am looking at from the few photos presented.......I am seeing:
1: A standard "steel-cases" Romanian 8x57 FMJ Cartridge that looks like it did not fully chamber (probably due to "laquer-fowling"in chamber......or possibly due to "out-of-battery" firing due to firing-pin being stuck in the forward position). The case appears to have both/two Berdan-primer flash-holes present (standard-case).....and fired when almost fully chambered.
There may also be some slight deforming of the "neck" of the case (or "case-mouth") which may have caused it to not fully chamber.

2: When the primer-fired.........did this happen as the cartridge was chambered (?).....or when you pulled the trigger (?).

3: I am guessing (as I have not seen one of the semi-only bolt-groups disassembled) that the bent part in the photo is the firing-pin-extension (?)........and if so, could have caused the firing-pin to protrude as the bolt started to close. Similar to a fixed firing-pin on some submachinegun bolts.

4: There does not appear to be any damage to the barrel-extension....unk if there is an obstruction in the barrel....(?-look.)

Just from viewing these photos, and the limited information provided.......I can only guess at this point that:
1: The weapon fired "out-of-battery" due to the firing-pin sticking in the partially forward position due to a bent firing-pin-extension........or:

2: That the weapon was fired in a partially open/out-of-battery position when a slightly deformed cartridge-case was partially-chambered (but chambered enough for the semi-only hammer to be allowed to strike the firing-pin-extension) firing the primer with the bolt in the "un-locked" position on the barrel-extension. We won't know until MauserMatt posts more information ...........or:

3: That the SA42 fired in a slightly out-of-battery position due to a combination of "bolt-bounce" (a problem in FA MG-42s without the anti-bounce element being installed inside the bolt-carrier)....which could have possibly allowed the firing-pin-assembly w/extension to move forward "if" the firing-pin retaining-spring was weak and allowed forward movement (IE: "Slam-Fire" effect ?). Does your barrel-assembly have free/full movement inside of your recever (?).

Last, with the primer firing......you were very lucky that the steel-case did not rupture due to pressure causing injury to yourself and anyone standing near you. I have seen this happen to a couple MG-42 owners firing guns without the aid of the anti-bounce element being installed inside the FA MG-42 Bolt-Carrier.
I can't see the full side-view of the cartridge at this time.......but it is odd that the bullet did not move.

Regards, RichardS in MI.
Blanksguy2001@chartermi.net

[MauserMatt]

Ok, I'll answer as best I can..

Standard Romanian ammunition was being used in my semi auto MG42. It has a Pirate modified bolt and a wiselite arms gripstick.

There was no obstruction inside the barrel. After I took the picture of the bullet still in the chamber I was looking for my steel rod that I carry with me to try to pound it out. My brother who was with me then informed me that he had already pulled it out with his hand. So it was not stuck in there very hard. The barrel itself has not had many of my own rounds go through it. I've never shot the gun until it's too hot to touch.

Yes that bent part is the firing pin extension.

As far as I know everything in the '42 was working fine. I've never felt resistance when pulling the charging handle, just the normal unlocking of the bolt from the barrel extension and then free movement backward.

I do consider myself lucky that there was no catastrophic explosion! And to tell you the truth I think this is the 2nd time this has happened. Though the last time I didn't pull the bolt apart. Both times the bullet didn't fire, just an exploded primer.. And actually I think I even found one of the primers laying in my pocket!!

I think I need to get Pirates upgraded bolt...

[bolex]

Matt--

Looking at your photos its a little tough to see all of the primer pocket of the cartridge case. It looks like a poorly manufactured Berdan primed case. Does the cartridge have the two flash holes in the back of the cartridge? If the two flash holes are not there and the primer is loaded into the casing. When the gun is in a locked position and with no flash holes in the cartridge case when stuck by the firing pin all of the primer gases will go into the firing hole and into the internal parts of your bolt and bend or break firing pins. That's my guess. I have seen this happen to at least two pistols in the pass three years. The culprit in both cases were no flash holes in the cartridge case (poor QA). --fjruple

Are the flash holes in the primer pocket?

[MauserMatt]

Yes, there are flash holes.

[MauserMatt]

And when I shake the cartridge there's still powder in it too..

[JBaum]

I don't understand why the cartridge was sticking out of the chamber, and was not fully in the chamber. Was there some obstruction in the chamber that stopped the cartridge from being shoved fully in? It had to be stuck on something if you say you were going to try to push it out, but that it came out by pulling on it.

[MauserMatt]

I don't know what could have gotten into the chamber.. This happened in the middle of a belt... And after the cartridge came out I of course checked the barrel and nothing there or in the chamber to hold it up..

I guess I just have a paradox on my hands...

[JBaum]

Did you check the cartridge to see if it was actually an 8mm mauser cartridge? Would fit back into the chamber after you pulled it out? Maybe it wasn't the correct caliber? Some cartridges are very close to each other, but are not compatible. It seems odd that the primer is missing, but the powder is still in the shell. A .308 cartridge is fatter than an 8mm mauser cartridge. Could it be a .308?

[MauserMatt]

Definitely not 308. It's marked just like any other Romanian cartridge I've fired through it....

I did find the primer at the range, but don't have it right now. It was pierced by the firing pin itself and of course blown out of the gun.

What would have bent that rod though? That's what I don't get.. Bent it and damaged nothing else...

[JBaum]

I don't have an answer for what bent the firing pin. I just don't understand why the cartridge didn't chamber properly.

[Blanksguy]

Could be a few reasons......and the reason why I asked for more (in depth) information from the owner of the gun.
Items such aslisted below (but not limited to) could be reasons for the cartridge nor fully-chambering :

1: Slightly bent/deformed case.
2: If the barrel was not fully forward...the angle of feed could have caused a cartridge to deform while loading.
3: Other causes not allowing a round to chamber are a dirty-chamber.....which laquered steel-cased 8x57mm happens sometimes.

As far as the bent-rod/firing-pin-extension (?) ......again....I go back to asking exactly what happened in detail during firing (?)....and loud-noises (?)....hard moving-parts (?).......did bolt assembly recoil-hard (?).... etc. ........so many questions ("ifs"), and so little time.

Regards,
RichardS in MI.
Blanksguy2001@chartermi.net

[salt6]

I can see the flash holes but do they go all the way through? Check your firing pin hole to see if there are gas marks/burns.