AK owners inspect your firing pins.

[DABrackett]

I hope my concerns are not BS because I genuinely want to help people avoid problems before I need to fix them; or worse, they cannot be fixed.

Attached are photographs showing what I found.

Note the flattened, sharp edge firing pin tip. Also note that the firing pin is bent and the back is highly deformed from impact with the hammer which is also grooved from the impact (photo). Note the crescent cut in the retaining pin formed when the firing pin departed the bolt. The picture of the bolt shows the "pressure relief" notch that just intersects the edge of the primer and would be filled by the primer metal when under pressure and compare that to the space provided by the firing pin hole and decide where 50,000 psi would rather go if the pin ruptures the primer. After I replaced the firing pin I test fired the gun and had a case rupture. The headspace on the 7.62x54R is set by the rim not the shoulder. This is why I cast the chamber to see if it was damaged or out of specification. It turns out that the ammunition may have been mislabeled. Chamber measurements were correct for 7.62x54R (Russian) but the ammunition was about 0.010 short at the shoulder making me think the ammunition is really 7.62x53R (Romanian).

Be careful, there is a lot of BS out there.

 

[chucklenut]

ive never heard of this before

 

[DABrackett]

Well it was on a psl/dragonov. Could have been a home build with barrel depth not set right or whatever. Any firearms is capable of having a heads space issue. The pin holing the firing pin in could have been comprised or a home made pin that was not heat treated or just a flawed surplus retainer pin.

Plus for the firing pin to push the hammer back bounce off of and or around the recoil spring and still have the balls to break through the dust cover and fly past the shooter just sounds like BS to me I just don't see it happening.

Here is some useful math for the intellectuals:

The firing pin weighs 105 gr (bullet) and is a snug fit in the bolt which is ~4-inches long (barrel). Assuming only around half of the pressure of the round 7.62x54R passed through the firing pin hole it would be the equivalent of a 9mm parabellum propelling a 105 grain steel rod. My personal feeling is it is capable of passing through both sides of the receiver if it didn't have anything in the way to deflect it like a hammer and a loose dust cover.

 

[Jeddak]

Was it a PSL or a SVD? From the pics it looks like a PSL.
Also, I do not know if it is lighting, but the receiver seems to have a bulge on the right side, in the pic with FCG.

 

[DABrackett]

Thanks for the constructive input!
The receiver is a FPK Dragunov (Romanian) imported by TG. I have little knowledge of the history of the firearm. I will be test firing it again once I get in-spec ammo.

 

[bulletpaluza]

I hope my concerns are not BS because I genuinely want to help people avoid problems before I need to fix them; or worse, they cannot be fixed.

Attached are photographs showing what I found.

Note the flattened, sharp edge firing pin tip. Also note that the firing pin is bent and the back is highly deformed from impact with the hammer which is also grooved from the impact (photo). Note the crescent cut in the retaining pin formed when the firing pin departed the bolt. The picture of the bolt shows the "pressure relief" notch that just intersects the edge of the primer and would be filled by the primer metal when under pressure and compare that to the space provided by the firing pin hole and decide where 50,000 psi would rather go if the pin ruptures the primer. After I replaced the firing pin I test fired the gun and had a case rupture. The headspace on the 7.62x54R is set by the rim not the shoulder. This is why I cast the chamber to see if it was damaged or out of specification. It turns out that the ammunition may have been mislabeled. Chamber measurements were correct for 7.62x54R (Russian) but the ammunition was about 0.010 short at the shoulder making me think the ammunition is really 7.62x53R (Romanian).

Be careful, there is a lot of BS out there.

So the firing pin never left the bolt?

Also only a fraction of the total pressure is capable of leaving the through the flash hole to hit the bolt face/ firing pin. Now that we know it was chambering the wrong round, it adds a whole new set of possible causes to this outcome.

 

[DABrackett]

So the firing pin never left the bolt?

Also only a fraction of the total pressure is capable of leaving the through the flash hole to hit the bolt face/ firing pin. Now that we know it was chambering the wrong round, it adds a whole new set of possible causes to this outcome.

Yes, the firing pin left the bolt after shearing through its retaining pin and passing by the hammer cutting a notch in it.

 

[DABrackett]

So the firing pin never left the bolt?

Also only a fraction of the total pressure is capable of leaving the through the flash hole to hit the bolt face/ firing pin. Now that we know it was chambering the wrong round, it adds a whole new set of possible causes to this outcome.

The round fired after the firing pin repair ruptured at the neck but there was no gas leak around the casing because it was sealed in the almost identical chamber behind the neck. Given the round is headspaced by the rim and not the shoulder, I don't think it is very likely that there is another avenue for this to occur such as casing separation.

 

[bulletpaluza]

Yes, the firing pin left the bolt after shearing through its retaining pin and passing by the hammer cutting a notch in it.

I guess just about anything is possible with firearm failures. This is just a very odd chain of things to happen glad the shooter was ok and all were safe.

 

[BangBang]

I wonder if the company will send you replacement parts AND a new pair of underwear if this happens to you?