casing with the neck came off

Boltcarrier

Boltcarrier

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I have a question and wonder if you ever had this experience and what you think

I was shooting my SKS with 7.62x39 cal cartridge by PMC Bronze and I loaded three cartridges and after firing the first one, and second one, the third one got stuck leaving approx 1/4" outside of the chamber. The bolt was blocked and it cannot move at all. when I looked at the second fired shot casing I noticed that the neck of the casing is gone, completely cut off. so when I kind of hammer the bolt backwards with my fist, it dislodged the bolt (I removed the spring and dust cover) and the cartridge, the part of the neck from the second cartridge was stuck in the chamber. I believe that was the cause of the third cartridge getting stuck in the chamber without being able to chamber properly.

fortunately the third cartridge did not explode because about a quarter of the rim end was exposed from the chamber.

I wrote to PMC about it and they didn't respond.

I would like to have your opinion on this and if there's anyway I can avoid this happening again because I think next time I may not be as lucky and ended up with the cartridge exploding in the chamber.

thank you for your time.
 
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I've had something similar with some 7.56. I've been told the chambers opened up a bit allowing for over expansion which rips the brass. Can apparently be fixed by filing back the barrel end. I'd be interested to know if anyone has any other ideas.
 
LastStandContracting said:
I've had something similar with some 7.56. I've been told the chambers opened up a bit allowing for over expansion which rips the brass. Can apparently be fixed by filing back the barrel end. I'd be interested to know if anyone has any other ideas.
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What in the world is "filing back the barrel end"?
 
It's a sloppy milsurp chamber. PMC isn't going to reply and admit any sort of liability. Especially because it's impossible to know if it was the ammo or the rifle without examining the chamber and headspace.

OP if you are worried check headspace then get a chamber casting done and measure to make sure the chamber is spec.

Always wear eye protection no matter the rifle, but especially with surplus semi autos.
 
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OK, there was a separated case. The neck remained in the chamber, preventing the next round from chambering completely. The bolt could not close as a result.
Fortunately, when the bolt stopped moving forward against the jammed round, the firing pin did not bounce against the primer hard enough to ignite it. That would not have been a good thing.
Why did the case fail? Really hard to say.
You could try a FIELD gauge, and see if the headspacing is badly out of spec. If it is, from a practical standpoint, there isn't much you can do about it. Is the chamber within specifications? Whose specifications? Doubt if you are going to be able to find out what the specifications were 65 years ago in the Soviet Union.
You could find out if PMC ammunition is made to SAAMI or CIP specs, but those specs may have nothing to do with your rifle.
I would suggest you use standard M43 ball ammunition. The surplus steel cased stuff sold cheap by the case.
You might never have another case separation with the PMC. Who knows?
 
Getting that torn off neck out is prime opportunity to totally wreck that chamber! Look up ways to do it, like using a broken case extractor or cerro-safe. If you think you can poke it out with a rod from muzzle, you will 99% certainly gouge up inside. I have a "parts" rifle here that went through that exact line of thinking...
 
Potashminer said:
Getting that torn off neck out is prime opportunity to totally wreck that chamber! Look up ways to do it, like using a broken case extractor or cerro-safe. If you think you can poke it out with a rod from muzzle, you will 99% certainly gouge up inside. I have a "parts" rifle here that went through that exact line of thinking...
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Run a boresnake through from the muzzle, the neck will come out on the snake and will not likely scratch the chamber as it most likely separated at the neck base... really not a tough job.

Another problem causing a separated neck is corrosion (moisture induced), between bullet and neck.

tiriaq said:
What in the world is "filing back the barrel end"?
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I think he means "setting back" the barrel...
 
A brush on a rod might catch the neck as well. The round being slammed in would have jammed the case neck firmly into the chamber.
Probably referring to setting back. Setting back a SKS barrel would be complicated by the gas system. It would have to be done a full turn, and then the gas system parts would have to be altered, in addition to the chamber being reamed. And that assumes that excess headspace was the problem.
 
tiriaq said:
A brush on a rod might catch the neck as well. The round being slammed in would have jammed the case neck firmly into the chamber.
Probably referring to setting back. Setting back a SKS barrel would be complicated by the gas system. It would have to be done a full turn, and then the gas system parts would have to be altered, in addition to the chamber being reamed. And that assumes that excess headspace was the problem.
Click to expand...

Aaaaaanndd.... the SKS is not worth it.
 
tiriaq said:
What in the world is "filing back the barrel end"?
Click to expand...

Remove the barrel and file off the end to set it back and reduce the head space.
I was interested too see what others thought because that info comes from someone who's focus was field fixes so I wasn't clear on whether it was best practice.
 
LastStandContracting said:
Remove the barrel and file off the end to set it back and reduce the head space.
I was interested too see what others thought because that info comes from someone who's focus was field fixes so I wasn't clear on whether it was best practice.
Click to expand...

The shoulder would have to be cut back to allow the barrel to turn in further. The shank has to be shortened by a similar amount. Then there is the issue of the gas system needing to be indexed top-dead-center. The barrel would have to be turned in at least one full turn. And headspace adjusted with a reamer.
This sort of thing can be done, with a lathe. It is somewhat more complicated than filing a bit off the end of the barrel.
 
A 400$ fix on a 200$ Gun chop it up and buy another one if you are concerned about safety, how many rounds have you shot thru it ? . If you have shot 100’s of rounds thru it and it has never happened then it was just a incident . If you are concerned about headspace which will be at the max for sure just mike some fired cases that will tell you all you need to know
 
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