So it finally happened !

[Tripodmvr]

1. Headspace might have enlarged.
2. Locking lugs set back or might have cracked.

[oafpatroll]

Miles out of my lane here but it seems unlikely to me that absolutely no damage would have been done. If the pressures really were above 200k PSI that would be north of 300% that of a proof round. 

[janfred]

That may be true, but the old .303's all have plenty of vent holes which is not taken into account by quickload. 200kpsi pressure would definitely have resulted in a rapid unscheduled disassembly.

If there is no bulge in the barrel, and the locking lugs are not cracked, then I don't think the pressure got even close to these calculations.

If the pressure got to 99kpsi, the brass would have flowed so much that I doubt extraction would be possible.

A photo of the fired cases and the case heads in particular should tell some of the story.

Whatever we think, the rifle has to be checked by a competent gunsmith as per Tripod's post above.

[Treeman]

Thats a large rifle primer, the hole is stretched wiiiide .
20240925_165355 by David Frank Allen, on Flickr

[Tripodmvr]

Bolt face and extractor all right? I once shot a 270 reload in my 7x64 by mistake. Battled to get the case out and broke the extractor. Luck was on my side and the gunsmith got a replacement.

[Newton]

That may be true, but the old .303's all have plenty of vent holes which is not taken into account by quickload. 200kpsi pressure would definitely have resulted in a rapid unscheduled disassembly.
If there is no bulge in the barrel, and the locking lugs are not cracked, then I don't think the pressure got even close to these calculations.
If the pressure got to 99kpsi, the brass would have flowed so much that I doubt extraction would be possible.
A photo of the fired cases and the case heads in particular should tell some of the story.
Whatever we think, the rifle has to be checked by a competent gunsmith as per Tripod's post above.

"but the old .303's all have plenty of vent hole"
This was a P14 - similar to a Mauser - NO idea where "vent-holes" would be in this action ?

I am also not sure why there should have been a - "bulge in the barrel"  ?

I also have no idea how Treeman would not have noticed a difference in sound and recoil ?
Those cases shown exhibit EXTREME pressure

IF you had looked at this post of mine ...

.308 to the limit

You would have noticed that they took these .308 loads up to 103.785 psi ( ESTIMATED )
All approximations of course as they did not use any proper pressure test equipment
However ... brass was easily extracted and there was no "brass-flow"

Pushing the 308 Win into 300 Win Mag Territory (Bat Machine, Alpha Munitions)

Without proper test equipment and careful measuring - EVERYTHING is just pure speculation and thumb suck

Would a gunsmith sign a no-disclaimer on certifying this rifle back into service ?

Personally I would scrap it !

[janfred]

A pierced primer the gas escapes through the small hole in the bolt body. If the case ruptures the gas escapes via the ejector slot. Also around the bolt head

This hole lines up with the bolt relief hole.

Alpha Munitions cases are unique in that the case head is much harder than standard brass cases, hence the ability to withstand much higher pressure without flowing. They would not have had the same results with Lapua or Hornady brass.

[Treeman]

The amount of thought and learn from past experience in just those two pictures - astounding.

[Newton]

The amount of thought and learn from past experience in just those two pictures - astounding.

The golden question of course ...
DID any gas flow out / escape from these vent holes ?
DID Treeman notice any gas escaping from the vent holes ?

IF not ? can we assume that the rifle / action did NOT experience an over pressure event ?
At the sorts of pressures mentioned ( assumed )  I would find that quite strange ?

[big5ifty]

If you have sulphur, you can do a chamber cast. Quick and easy, Google how.

The dimensions you get from that are an accurate reflection of actual, but that doesn't tell you if the integrity is compromised.

You have a duty to ensure that the action is still safe, or scrap. For the sake of everyone who will pull the trigger on that rifle, now or in future.

Send it in for testing, and if that's too expensive, scrap it.

It's just a thing, things break and can be replaced. Body parts and life, not.

[oafpatroll]

If you have sulphur, you can do a chamber cast. Quick and easy, Google how.

I've tried the sulphur method recently and it was incredibly effective. Stinky but effective.

You have a duty to ensure that the action is still safe, or scrap. For the sake of everyone who will pull the trigger on that rifle, now or in future.
Send it in for testing, and if that's too expensive, scrap it.

Couldn't agree more. Something that has been exposed to conditions so far wide of it's design parameters is suspect. Given it's a rifle action and if its been compromised it's got the potential to cause some real physical harm.   

[janfred]

Judging by the photo of the case heads, it was definitely way overpressure for the primer pockets to be enlarged that much. An engineer could probably do some calculations to estimate the pressure. The scuff marks also show that some brass flowed into the ejector slot. Also some flowed to the unsupported rim area downwards. I am really surprised that the cases extracted easily.

I suspect that the energy absorbed by the flowing brass saved the day.

Definitely need to have it inspected by a competent gunsmith.

[Treeman]

The chamber was oversize, a problem we were going to look into. I have now noted that the shot brass will not fit into an Epps sizing die.
Perhaps that answers some questions without a gunsmith.

[Newton]

The chamber was oversize, a problem we were going to look into. I have now noted that the shot brass will not fit into an Epps sizing die.
Perhaps that answers some questions without a gunsmith.

Perhaps ?
But .. perhaps not the most important ones ?