Out of battery question w/pictures

[tigrr]

Is that not the primer body in the picture with the brass case in the chamber?

 

[Jon.]

No the primer was awol. The only part left was the anvil which was on the guys sleeve.

 

[Cameron SS]

Never found the whole primer, just the anvil.

Just to throw another twist in, I managed to get it apart today. Barrel extension pin seems to be sheared off clean. I don't know if that was factory as I've never taken the barrel off, but I also couldn't find the rest of the pin, and it's a pretty self contained unit. So that explains why in the photo the alignment was off.

Case is in pieces but looks to have separated below the shoulder.

So question, could the lack of barrel extension pin throw off the alignment, and that cause the bolt to be almost but not quite engaged? Not enough of a lockup time to let the pressure out? Blowing the bcg backwards causing the rest of the damage? Something like that?

Certainly possible.

For the barrel extension to be that far out you would be talking 15 to 20 degrees or so of misalignment. Its also possible that it shifted as part of the detonation/mishap.

I thinknif your front sight/gas block was misaligned by 20 degrees it would be very obvious visually. So the question is, with the extension misaligned did the gas block look like it was 12 oclock? If so, then Id be rather certain it was installed incorrectly and the gas block was indexed at 12 oclock afterwards.

If both the gas block and barrel extension are misaligned to the same extent, and you didnt notice a 20 degree misaligned gas block prior, then the shift probably happened during the event.

A few people commented about the gas tube holding the barrel/extension in alignment. I cant agree. Gas tubes are super soft and will flex and bend significantly offering little resistance to a barrel trying to rotate in the receive.

I just backed the screws off a gas block and was able to rotate it almost 90 degrees before the case tube really started to protest.

The trouble I have with this barrel extension theory is that if everything was tight than this would have been a problem from day 1 with every shot fired. So the question still remains, which was this shot different? What ALSO failed to contribute to the event. Was it just wear and tear? Was the barrel extension, lacking an index pin, vibrating further and further out of alignment with every shot?