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

[Clabdor]

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?
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Different Bolt : how do we buy PTG aftermarket bolts and put them in our guns? which is a different bolt
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OP, is your Bolt Vented?

Not sure. I'll check tomorrow if I can inspect the bolt all the way around. I like the idea of a vented bolt going forward.

 

[Clabdor]

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'.

Happy to answer whatever questions anyone has. I've relayed everything I can think of, but many (if not all) of you have deeper expertise on this than I.

 

[Coyotefurharvester]

If it was/is simply a manufacturer QC mistake, WOW.

 

[Clabdor]

FYI. Starline says to tumble their cases before firing.

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

That makes two of us........

 

[Evlshnngns]

You are being redirected...

I believe the action splitting is a good design. Far better that than lugs shearing.

 

[Thud]

The gun had a total of about 140 rounds fired through it. I cleaned the gun after the last set of rounds, so it would have had approximately 12 shots down the tube before it blew.

What is your cleaning routine. Reason I ask had a friend with a similar experience. He was shooting a 6 competition match. Slight over bore cartilage and shot a similar string and same result. Result was after talking to other shooters, some had found that the carbon ring was present before the problem and they fluffed it off.

 

[ELR LVR]

What is your cleaning routine. Reason I ask had a friend with a similar experience. He was shooting a 6 competition match. Slight over bore cartilage and shot a similar string and same result. Result was after talking to other shooters, some had found that the carbon ring was present before the problem and they fluffed it off.

Hard to believe a carbon ring would build up to this extent in less than 200 rounds for this situation.
That is interesting though

 

[jpjulian]

Late to this party but have read all the posts...... Does anyone know if Christensen uses a machined or cast action body? The edges of the failure area have a somewhat crystalline look which leads me to believe it is a cast part and the casting failed. I also agree with another poster and think the action cracked on a prior shot to the catastrophic failure. I also see something odd with the indentation on the primer in the bottom center fired case, (row of 3 above the 2 unfired rounds). It looks cratered and possible pierced.

 

[jxb]

A close up picture of the cracks would be helpful. Of the metal of the cracks . The metal in part of the crack looks a different color that tells me an existing crack.

This was what I first noticed, since it was catastrophic I'd have expected all the action splits to be the same color and look the same, they definitely do not. Those darker colors are usually an indication of a preexisting crack but really needs to be looked at by someone qualified that makes their living looking at splits/cracks.

The next thing I noticed was your other brass fired just before it there were no ejector marks and the primers were not flattened at all. However all the primers show deep strikes and those might be well within spec, but also cratering, some of the cratering severe. I believe this is an indication of substantial bolt thrust each firing. This could be a chamber not wiped/cleaned well after cleaning the barrel so there was slippage or simply new brass growing a lot in that chamber, or a combination of both.

Also would suggest getting a photographer to take in-focus macro photos of those cracks, they will know to use proper lighting. This would eliminate any shadows and show far more details as all your photos are slightly out of focus at the break in the action.

 

[Capt. Oblivious]

Very interesting and a nice looking rifle or was a nice looking rifle, at least the scope looks to be fine.
I doubt you could get a double charge or even enough H4831SC in that 280AI case to blow the action up, id get in contact with the manufacturer.

 

[Fast14riot]

Just taking a SWAG at this, but if the barrel had loosened enough, case captured by extractor to allow a proper firing pin strike but enough case head exposed that it was unsupported and resulted in catastrophic case head failure. Do these rifles have a larger chamfer on the chamber mouth to exaggerate the issue? Similar to the "glock bulge" on 40 cal pistol cases.

 

[old codger]

In pic 3/3 in post# 23 it sure looks like there was a pre-existing crack which then failed. Could be just a difference in lighting.

 

[DaveTooley]

That folks is high pressure. Cause to be determined.
You can see the imprint of the extractor on the edge of the counterbore.
The crack in the bolt referenced by DShortt is on the thin outer edge of the bolt nose by the ejector pin. Notice the brass flow into the ejector hole.
The case has developed a belt at the chambers edge.

 

[DaveTooley]

In pic 3/3 in post# 23 it sure looks like there was a pre-existing crack which then failed. Could be just a difference in lighting.

That crack is at one of the fault lines in an action. Those are the action screw in the bottom and the top of the lug ways. Also torn metal looks much different than what we're used to seeing.

 

[243winxb]

It was virgin brass so straight out of the box from Peterson. Given their reputation, I would be super skeptical of something in the brass. I did have another piece of brass from them that I couldn't get in my shell holder on my primer seater. It was the only one like that. I set it aside. We micrometered hat piece of brass and it was wider at the base then the others, but all of the charged rounds fit in the shell holder else we wouldn't have been able to get the primers in them.

My thoughts-
1.Defective brass failed?
The hot gas went thru the M16 extractor cut.
The vented gas split the receiver?

OR

2. Did the receiver fail first, because of improper heat treating?
Then the case head moved off the bolt face and case head ruptured?

I think #1

Best part, no one was injured.

 

[Doom]

That crack is at one of the fault lines in an action. Those are the action screw in the bottom and the top of the lug ways. Also torn metal looks much different than what we're used to seeing.

I agree that the discoloration if real may likely be an indication of a preexisting crack in pic 3/3 in post# 23 . A better picture would help. Also in that picture there is one of the vent holes. It's not clear to me that the vent hole goes completely through the wall!

 

[Will Henry]

I haven't read through the entire thread and probably have not seen all of the pictures but, as of page three, this is my guess:
It looks to me like the action was compromised during heat treat, then compromised even more by torque on an inside wrench. The incipient lengthwise cracking was primarily at the top of the right-hand raceway. I would expect the failure began with the second last shot and there was actually significant head clearance on the last shot.
The end result is kind of a culmination of events, a perfect storm, of sorts. Receiver not right from the start, damaged during barrel installation, damaged further by the firing of proof load, and finished off by normal used. A freak accident, in a way. I have seen some modern rifles and some not so modern, which were destroyed by severe overloads, and other which were destroyed by damage by the "gunsmith". These were rifles which had barrel threads which were too tight, or which had been damaged by the use of an inside wrench. They looked just like yours. They came apart at the receiver ring, split lengthwise. The cracks showed signs of being penetrated by solvent. In other words, they had been there for a while. The guns came apart suddenly, with what should have been a normal load.
Now, I have not seen your rifle personally. There also a chance I could be wrong (happens all the time!), but my guess is the action was flawed. WH

 

[Ringostar]

Several people mentioned wrong bullet in box, but others pushed off a 30 caliber. I haven’t looked into what is available from manufacturer, but What about a heavier 7mm bullet in same design? This could certainly increase pressure. Others mentioned a carbon ring building, which could explain the increasing velocities. Then suddenly having a heavier bullet jambing a carbon ring. Just some thoughts that I’m having.

 

[DaveTooley]

Here are pics of the rifle I have here. Eerily similar.
Note the extractor retaining pin that was pushed out with enough force that it bent the pin when it reached the action wall. Seems pressure is not distributed equally at the same moment. You can see the edge of one bolt lug with the edge rolled over slightly. All three of the other lugs were not deformed.

 

[358WCF]

What in the world is the hunk of copper looking stuff & how did it get there?

It looks like the barrel torqued when coming apart too... what looks like a feed ramp bevel & recoil lug are disoriented.

Clues or noise? Chicken or the egg?

Glad nobody was hurt. There seems to be a rash of these failures lately. Is it novice reloaders watching too many of the wrong Youtubes? Is it piss-poor QC at the manufacturers? Proof loads were mentioned a few times. Do rifle makers actually test fire rifles before shipping anymore?