Popped primer?

[TJNewton]

I was shooting my VZ2008 yesterday and had gone through one magazine and was starting on the second.  A few rounds into it the rifle jammed with the carrier stuck forward just enough that it had barely lifted the next round out of the magazine to chamber it -- several inches open from full battery.  There was nothing different about the last shot:  same recoil, same loudness.  There was a large amount of smoke swirling from the magazine and receiver.

I removed the magazine and removed the top end.  More smoke.  I didn't see any gouges or damage, but when I put everything back together, the carrier would stop about 3/4" from going into full battery.  It required significant force to push it in all the way.  I took it apart again and tried the action without the tension of the dust cover.  The locking lugs would drop normally, but the carrier would stick the same distance away.  I didn't want to force it again and packed everything up.

When I got home I saw that the firing pin was recessed and jammed.  I stripped the bolt and it took some tapping with a punch to remove the firing pin.  Nothing on the bolt or the firing pin looked damaged.  Regardless, I switched out the bolt and checked headspace and function; the new one was fine.  I first thought that the carrier wouldn't moved forward due to damage to the bolt but now believe that the problem was the jammed firing pin.  I didn't think of that until I'd replaced the bolt with the spare and packed everything away.  When I have time I'm going to reassemble the original bolt and give that another try.

This sounds like a popper primer.  I know it's fairly common with the SKS, and that it usually destroys the firing pin, although I've never had it happen to me.  I'm wondering if was indeed a popper primer or some other mechanical failure with the original bolt or its parts.  Anyone have any experience or thoughts with popped primers with this platform?

[RSR]

If your gun is not tabbed or fully tabbed (believe Obiwan recently discussed on that front), then it's possible to fire out of battery.  The "in-battery lever" is removed in every semi-auto version of this gun that I've seen. 

Standard questions here are what ammo, have a photo of the last fired case, etc? 

Slam fire or out of battery slam fire are also both potentially what happened.

Most likely culprit as to your not going into battery is that your broken firing pin interfered with your extractor going over the case rim, not a problem with the actual bolt itself.  (The short L arm of the extractor is what retains the firing pin from falling out the rear.)

However, your firing pin just breaking seems like the most likely occurrence from what you've posted, but certainly not 100% on that...  So personally, I'd disassemble the bolt, clean it and replace the firing pin and try again. 

[TJNewton]

The carrier is tabbed.  I had checked head space a while back and had shot a couple of hundred rounds just after that.  The rifle has about 1600 rounds through it with no prior problems.  As in "battery slam fire", do you mean that the firing pin may have been stuck forward as the bolt was going into battery, and that the fixed firing pin preceded the bolt just enough to cause the issue?  When I examined the bolt the firing pin was jammed in the recessed position.  I guess it's possible that the firing pin was first jammed forward and then got jammed back inside the bolt as a result.

The ammo was Wolf FMJ, WPA, I think.  I've had popped primers with Tula in my SKS, with milder effect, but never with Wolf and never with a VZ2008.  I didn't get a chance to look at the case since it was flung far forward of the firing line into other brass and steel cases.

That makes sense about the firing pin impeding the extractor.  The firing isn't broken, however.  I'll have to examine it more closely with a magnifying glass but it seems fine.  It was just wedged in tight.  I don't know if the channel is damaged.  I'll put it all back together and give it a try.  It's possible that the firing pin is slightly bent or gouged.  If it doesn't rattle completely freely or has any damage at all I'm going to toss it.  In fact, considering the risk-to-benefit, I think I'm just going to toss it regardless.  Nothing like a full 30-round magazine slam firing to ruin your day

[RSR]

A new member here shared pics of new firing pin that had issues recently causing it to pop past the extractor.  Give the firing pin a close inspection once disassembled vs those pics. 

But yes, an out of battery discharge would result from the loose firing pin setting off the primer prematurely and the same firing pin taking the bulk of the force from the discharge before the case fully seated against the bolt. 

Obiwan discussed how many tabs are actually too short to fully remedy issues.

You really need the fired case from moment of problems to diagnose.

Just spitballing here. 

[TJNewton]

Unfortunately, examining the case was an instant impossibility as it got flung 15 feet past the firing line into a sea of spent brass and steel.  I haven't yet tested the new set up, but it headspaces fine.  I'll also reassemble the bolt in question with a new firing pin and try that out, too. 

I've put near 8,000 rounds down these VZ2008's and this is the first "popped primer"-type occurrence.  I have had two issues with the broken bolt lugs, but have since fitted the bolts to remove any contact with the receiver.  The bolt failures did not happen with this specific rifle.  Could this be purely an example of bad ammo?  It was Wolf, but I know I've had a few popped primers (lots of smoke but no damage) with Tula through my SKS.  Tula has a reputation for popped primers.

Thanks for the insights.  I'll update as soon as I have time to go to the range.

[RSR]

Any signs of outward protrusions around the firing pin hole?  And the smoke is the primary reason you're going with a popped primer diagnosis?

I still think it's likely an extractor issue for it not going back into battery, but uncertain on what exactly caused your firing pin to break. 

[Wobbly]

I'm not a VZ guy, but just going by the description it sounds like the primers are being pierced. This usually happens when the bolt face exposes too much of the firing pin and the primer gets punctured. When that happens hot gasses shoot back around the firing pin and can jam it with small bits of brass, powder, etc. I'd want to see the last 5 cartridge cases fired in this gun to know for sure.