Not a great way to begin a thread on load development but....

[ELR LVR]

I m

The weird thing about SEE is, it's not something that can be easily replicated.
It's an 'alignment of the stars' thing at best.
So, I tend to believe that all manner of reloading mistakes get lumped into this category when no obvious explanation exists.
Perhaps this was a case failure. If so, it was a one- off case. Perhaps this was an overcharge. Given that the barrel would have to contain that excessive pressure and not the action, I'm not sold on that idea.
Unless something was involved that we've not been told, it will remain a topic of opinion and never 'resolved'.

must have missed the memo
What is "SEE" ?
---
BTW
I am thinking if his load was the same as the previous upper limit loads
it should have contained the pressure from a load that only showed primer cratering and no other signs of overpressure
I have loaded PLENTY over many years with the same primer cratering even flat primers as long as no Shiny rim or Ejector marks are present
even then, I have had it up to Flat primers, cratering AND Ejector marks
and still no mishaps (not saying that it's ok to load that way, but that those are the signs to back it off)
---
Wasn't there some Test Standard where they pressure test a gun by throwing a double charge or something like that in the gun and test fire it?
Or am I remembering that is the type of test for muzzle loader?

 

[DShortt]

Secondary Explosion Effect.

I won't spell all the details out here and it's highly controversial.
A quick Google search displays the theory.

 

[DShortt]

I m

must have missed the memo
What is "SEE" ?
---
BTW
I am thinking if his load was the same as the previous upper limit loads
it should have contained the pressure from a load that only showed primer cratering and no other signs of overpressure
I have loaded PLENTY over many years with the same primer cratering even flat primers as long as no Shiny rim or Ejector marks are present
even then, I have had it up to Flat primers, cratering AND Ejector marks
and still no mishaps (not saying that it ok to load that way, but that those the signs to back it off)

Agreed.

 

[GAnderson]

Confused, hows that blow up an action?
Unless you mean due to it
excessive headspace happened, even then, i've had plenty of case head seperations in rifles up to 7mm Mag and never had anything like this happen
However, my bolts are vented should something like over pressure or pierced primer happens and the pressure vents out the side of the bolt
maybe his bolt was not vented?
---
Different Bolt : how do we buy PTG aftermarket bolts and put them in our guns? which is a different bolt
---
OP, is your Bolt Vented?

I'm not aware of anyone that just buys a bolt from PTG and puts it in their rifle and goes to shooting it without checking headspace and having the bolt fit for proper headspace to that barrel/chamber. Maybe some do...??? I never have.

 

[ELR LVR]

I'm not aware of anyone that just buys a bolt from PTG and puts it in their rifle and goes to shooting it without checking headspace and having the bolt fit for proper headspace to that barrel/chamber. Maybe some do...??? I never have.

I understand, headspace is paramount
is that what you're suggesting though?
Excessive headspace and the case ruptured?
---
No offense intended but,
Within rocket science, try to be specific so we dont have to guess
I did not see that conclusion posted in your notes
I only noticed a possible bolt switch mentioned and bolt thrust
---
to some it's basic common knowledge
to others, they dont even know what headspace is
---
Further, I have seen test results including those done by Mr. Ackley where
even a fully oiled case only produced maybe 900 lbs more bolt thrust
which is nothing compared to the 23,000 or so generated initially
So I'm trying to understand how you are suggesting excessive bolt thrust,
where did the extra bolt thrust originate from sir?

 

[GAnderson]

I understand, headspace is paramount
is that what you're suggesting though?
Excessive headspace and the case ruptured?

No, I am not suggesting anything...as stated in my original post "others suggested excessive bolt thrust" which I assume could be attributed to excessive headspace. My suggestion was to check and be sure that the bolts(his and his son's) maybe somehow got switched as it sounds like they were shooting together at the time this happened...wrong bolt in wrong rifle...Just a thought that could have lead to the excessive bolt thrust theory.

 

[DShortt]

Confused, hows that blow up an action?
Unless you mean due to it
excessive headspace happened, even then, i've had plenty of case head seperations in rifles up to 7mm Mag and never had anything like this happen
However, my bolts are vented should something like over pressure or pierced primer happens and the pressure vents out the side of the bolt
maybe his bolt was not vented?
---
Different Bolt : how do we buy PTG aftermarket bolts and put them in our guns? which is a different bolt
---
OP, is your Bolt Vented?

Think about the brass, chamber, and bolt head.
How exactly does the Pic you posted reptesent 'bolt venting'?

Not trying to 'bust your chops' but that looks like disassembly/reassembly access to me.

How's it going to vent pressure from anything but a pierced primer with the case head held against the bolt head with 50,000 lbs of pressure or more?

 

[dellet]

Oh I'm sure there was excessive bolt thrust but the question is when and what effect did it have on the outcome. What sequence did all this happen. Interestingly I've had other high pressure events where the case didn't rupture (non Sako or M16 extractors) and the tenon and bolt nose were expanded but the receivers stayed together. On the action I have here there's no deformation of the action lugs or bolt lugs.

Here's my guess of the sequence of events.
Pressure spikes expanding the tenon, sending a shock wave/ load to the receiver.
Almost simultaneously the case ruptures releasing high pressure gas into the area around the lug area.
Increasing the load on the receiver. I think both put a load on the receiver at the same time. A double whammy.
Bolt thrust goes up. But how does that contribute to the radial load on the receiver?
Next the receiver splits.

You can see the brass flowed and formed a belt in the counterbore and flowed into the ejector pin hole. My guess it shows how far below the bolt face the ejector can travel.

The 3rd ring of steel is missing due to the extractor design. Thats the path of least resistance. Once pressure was outside the bolt face, the pressure chamber was the action Itself, which apparently is not too strong. Built for horizontal thrust, not internal expansion.

 

[ELR LVR]

Think about the brass, chamber, and bolt head.
How exactly does the Pic you posted reptesent 'bolt venting'?

Not trying to 'bust your chops' but that looks like disassembly/reassembly access to me.

How's it going to vent pressure from anything but a pierced primer with the case head held against the bolt head with 50,000 lbs of pressure or more?

I am thinking with that much overpressure
it would certainly pierce the primer, the original post shows no primer and the side of the case blown out where the extractor is, which to me looks like he still had a contained vessel with no other means of venting
Let us suggest we put a 64,000 psi Over-pressure pop valve on the side of the chamber
---another avenue for pressure to relieve itself, is likely enough to prevent an action splitting

with no other means of venting, then yes there is no other avenue for pressure to escape
and of course, something else will have to give, The action, the barrel or the bolt lugs.

 

[DShortt]

The 3rd ring of steel is missing due to the extractor design. Thats the path of least resistance. Once pressure was outside the bolt face, the pressure chamber was the action Itself, which apparently is not too strong. Built for horizontal thrust, not internal expansion.

I agree.

But.

Explain to me how the head of that piece of brass was literally extruded into the ejector hole enough to leave a protrusion.

Soft brass is one thing. That was some SERIOUS bolt thrust for some reason.

I'm still thinking contaminated case wall.

 

[DShortt]

I am thinking with that much overpressure
it would certainly pierce the primer, the original post shows no primer and the side of the case blown out where the extractor is, which to me looks like he still had a contained vessel with no other means of venting
---another avenue for pressure to relieve itself, is likely enough to prevent an action splitting
with no other means of venting, then yes there is no other avenue for pressure to escape
and of course, something else will have to give, The action, the barrel or the bolt lugs.

Pierce it?

The pictures show the primer completely missing.

Which indicates to me that the primer exited along with the extractor.

Again, points to excessive bolt thrust.

What caused it?

That's the question.

 

[ELR LVR]

No, I am not suggesting anything...as stated in my original post "others suggested excessive bolt thrust" which I assume could be attributed to excessive headspace. My suggestion was to check and be sure that the bolts(his and his son's) maybe somehow got switched as it sounds like they were shooting together at the time this happened...wrong bolt in wrong rifle...Just a thought that could have lead to the excessive bolt thrust theory.

Where is the excessive thrust
........coming from?
that would cause a different bolt to have more thrust.... than it would to the original bolt?

 

[ELR LVR]

Pierce it?

The pictures show the primer completely missing.

Which indicates to me that the primer exited along with the extractor.

Again, points to excessive bolt thrust.

What caused it?

That's the question.

I'm sure the primer pierced first, having a pressure differential on the other side, allowing a path of less resistance
Then once the bolt cavity was pressurized
if the bolt was not vented, it still contained the existing pressure
which THEN, blew the whole entire primer out the side as the case ruptured to try and vent through the extractor
---
or the primer simply spit out the back as the action split and the barrel moved forward
I'd like to see the primer myself to see if there is a hole in it the size of the firing pin hole

 

[dellet]

I agree.

But.

Explain to me how the head of that piece of brass was literally extruded into the ejector hole enough to leave a protrusion.

Soft brass is one thing. That was some SERIOUS bolt thrust for some reason.

I'm still thinking contaminated case wall.

It’s two different questions, I responded to @DaveTooley post concerning full ring bolts not failing under the same circumstances.

High pressure is absolutely what started the event.

 

[Dufas]

Case head fail.

 

[DShortt]

Look at the bolt face.

It is cracked at the ejector. The case head has literally extruded into the ejector hole. The ejector is stuck in the cavity. The firing pin appears to be stuck in the bolt body.
Yes, the extractor blew out and the case head failed as a result.

I still don't see an explanation for overpressure.

I see a lot to explain excessive bolt thrust.

And I'm aware of a short list of causes.

A contaminated case body ranking very high on that short list.

Lesson here?

Make sure your case bodies are clean and dry if you choose to run high pressure loadings.

 

[tdogg]

I'm not going to claim to know anything about this type of failure, I'm not a ballistician or a gunsmith. I didn't even stay at a Holiday Inn last night.

My opinion is bolt thrust alone didn't cause this failure, the case head extruded into the ejector due to pressure. Look at the case body that extruded outward just in front of the case head (between the bolt and barrel), that took a lot of pressure. It found the weakest link, blew out the extractor, and then the action came apart as a result. I'm guessing there was something obstructing the barrel which caused the pressures to be contained, it built too much pressure or took too long to expel the projectile, and havoc ensued.

Cheers,
Toby

 

[jelenko]

FYI. Starline says to tumble their cases before firing.

So far I've ignored that. Maybe not from now on.

 

[jelenko]

I'm not going to claim to know anything about this type of failure, I'm not a ballistician or a gunsmith. I didn't even stay at a Holiday Inn last night.

My opinion is bolt thrust alone didn't cause this failure, the case head extruded into the ejector due to pressure. Look at the case body that extruded outward just in front of the case head (between the bolt and barrel), that took a lot of pressure. It found the weakest link, blew out the extractor, and then the action came apart as a result. I'm guessing there was something obstructing the barrel which caused the pressures to be contained, it built too much pressure or took too long to expel the projectile, and havoc ensued.

Cheers,
Toby

Hmm. As someone mentioned, maybe something from the round just before.
Or a case that was too long.

 

[DShortt]

I'm not going to claim to know anything about this type of failure, I'm not a ballistician or a gunsmith. I didn't even stay at a Holiday Inn last night.

My opinion is bolt thrust alone didn't cause this failure, the case head extruded into the ejector due to pressure. Look at the case body that extruded outward just in front of the case head (between the bolt and barrel), that took a lot of pressure. It found the weakest link, blew out the extractor, and then the action came apart as a result. I'm guessing there was something obstructing the barrel which caused the pressures to be contained, it built too much pressure or took too long to expel the projectile, and havoc ensued.

Cheers,
Toby

OK.

Then that theory relies in the barrel being unusually stout/flexible. Able to absorb an unusually high pressure event.

I'm not keen on accepting complex causes. Personal experience has taught me otherwise.

The OP admitted that he pulled the brass straight out of the container and loaded it on the upper published limits.

I subscribe to the most likely scenario. Which is the case wasn't clean enough to adhere to the chamber wall.

The over pressure situation relies on the barrel being overly stout/flexible. So stout and flexible that it split the receiver at the threads and also resulted in excessive bolt thrust evidenced by the condition of the bolt face.

So that means, the barrel was exceptional AND the case somehow slid rearward under the excess pressure.

You all believe whatever you wish.

I'm not keen on multiple causes.

Occam's Razor.