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Joined: Jan 2002
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Sidelock
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Sidelock
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That is serious over pressure, not just a little bit. Looking at the head of that shell I'm in no way surprised that the chamber let go.
SRH
May God bless America and those who defend her.
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Sidelock
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Sidelock
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Wish I had more details of this burst, courtesy of David Trevallion. It was presumed to be an over-pressure reload which blew out the lateral wall of the chamber. Possibly a properly brazed medial wall-wedge joint is stronger than the lateral wall? 
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Sidelock
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Sidelock
Joined: Jan 2004
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r.
Possibly a properly brazed medial wall-wedge joint is stronger than the lateral wall?
I would expect so - if the thickness of the steel was the same on both sides. But that's the problem. How much steel can the braze joint replace? Not enough in this case. I really don't want to claim allegiance to any particular hypothesis for the gun in question, but aren't all blown guns the product of "over pressure"? At least, relative to what that particular gun can hold, that is, in fact, absolutely the case. Whether the gun was over charged or the barrel understrength, the result is the same. In this case, there appears to be a plenty of reason to question fault with the gun. the anomalies with the case simply shows what happens when an a case becomes unsupported (because half the chamber disappeared). So I don't think it is really possible to convict the reload of overcharging. Just 2 cents from the sidelines.
_________ BrentD, (Professor - just for Stan) ![[Linked Image from i.imgur.com]](https://i.imgur.com/qclHjMQ.jpg)
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Sidelock
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Sidelock
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Now that we realize that the shell shows signs of extreme pressure, and was a reload, all bets are off and we are back at square one. By the way, Drew's assessment of the LCSCA forum matches the assessment I mentioned to the moderator probably ten years ago which was brushed aside. I assume Reverend Drew was also brushed aside. I don't go there, and I don't pay dues, even though I shoot the guns and like the members.
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Sidelock
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Sidelock
Joined: Dec 2001
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Has anyone used the word inclusion? I just blued a D Parker that had what I thought was a pit near the muzzle but it turned out to be a flap of metal cause (dirt in the metal) MY industrial experience show a tiny drop of "dirt" can cause a lamination several feet long.
bill
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Sidelock
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Sidelock
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Manganese Sulfide Stringers Bill Different from slag, which may have been the Parker issue. This was posted a long time ago by Robert Rambler. 1895 Ithaca Crass with damascus barrels that were being cleaned up for reblueing. Initially just a small pit on the surface of the barrels, quickly grew into what you see here as polishing continued. Inside the barrels are bright and smooth, giving no indication of a flaw. 
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Sidelock
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Sidelock
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....lifting of the primer from the pocket[/b], flattening of the primer against the breech face, and deep striker indentation, especially in comparison to shells of the same batch, as evidence of excessive pressure.... Just on speculation, the primer of the blown shell does not appear any more flattened than the sample fired shell next to it. I think the good fired shell is showing a bit of primer flow around the firing pin, maybe a bit warm anyway for the clearance around that firing pin fit up. The lifted primer and the apparent outward bulge on the primer near the striker indentation may have happened as the headspace started to increase as the chamber failed. I do not believe the primer striker indentation area had more strength than the failed barrel, maybe the rim and primer stopped distorting as the pressure dropped when the chamber failed. I would think the plastic hull sealed the entire chamber, from breech to opened crimp, but the plastic failed as the barrel failed in the same direction as the barrel failed, no plastic flowed back into the defect between the rib and barrel. It tore outward, and the plastic hull does not appear to have burned through and thus reaching the steel to burn it. I still think the dark color is from long term corrosion for two reasons. There is bright metal where the barrel failed away from the rib even though it was exposed to the same conditions as the suspected failure area. And second, it does not appear that the bore cleaner removed the dark coloring as if it were only powder fouling. It's always appeared to me that braze is still bonded to the rib and corrosion ran along the barrel. Only guessing Doc Drew because it is interesting, take care.
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Joined: Jan 2004
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Sidelock
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Sidelock
Joined: Jan 2004
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....lifting of the primer from the pocket[/b], flattening of the primer against the breech face, and deep striker indentation, especially in comparison to shells of the same batch, as evidence of excessive pressure.... Just on speculation, the primer of the blown shell does not appear any more flattened than the sample fired shell next to it. I think the good fired shell is showing a bit of primer flow around the firing pin, maybe a bit warm anyway for the clearance around that firing pin fit up. The lifted primer and the apparent outward bulge on the primer near the striker indentation may have happened as the headspace started to increase as the chamber failed. I do not believe the primer striker indentation area had more strength than the failed barrel, maybe the rim and primer stopped distorting as the pressure dropped when the chamber failed. I would think the plastic hull sealed the entire chamber, from breech to opened crimp, but the plastic failed as the barrel failed in the same direction as the barrel failed, no plastic flowed back into the defect between the rib and barrel. It tore outward, and the plastic hull does not appear to have burned through and thus reaching the steel to burn it. I still think the dark color is from long term corrosion for two reasons. There is bright metal where the barrel failed away from the rib even though it was exposed to the same conditions as the suspected failure area. And second, it does not appear that the bore cleaner removed the dark coloring as if it were only powder fouling. It's always appeared to me that braze is still bonded to the rib and corrosion ran along the barrel. Only guessing Doc Drew because it is interesting, take care. Agreed. Yours is more detailed description of what I was thinking and said.
_________ BrentD, (Professor - just for Stan)
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Sidelock
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Sidelock
Joined: Jan 2002
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I really don't want to claim allegiance to any particular hypothesis for the gun in question, but aren't all blown guns the product of "over pressure"? At least, relative to what that particular gun can hold, that is, in fact, absolutely the case.
the anomalies with the case simply shows what happens when an a case becomes unsupported (because half the chamber disappeared). So I don't think it is really possible to convict the reload of overcharging.
Just 2 cents from the sidelines.
Brent, I take "over pressure" as referring to more pressure than the gun was built to handle. Gun passes proof, which is extreme over pressure . . . but fails somewhere in the future. Maybe the result of metal fatigue or a flaw that the proof load didn't reveal. For example, I know of one case in which a modern Spanish gun (reputable maker) failed, fired with a factory load. Several inches forward of the chamber. No indication of an obstruction. Examination revealed that barrel wall thickness where it blew was something like .014. Yet it had been shot for a long time before the thin spot blew. Unless we assume an overpressure factory load, that failure was the result of a flaw in the barrel boring process, which left the thin spot in question. Hard to tell why it blew then rather than sooner, or how it managed to survive a proof load.
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Sidelock
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Sidelock
Joined: Jan 2006
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The answer to the cause is really quite simple except to those that refuse to see it....
1908...time worn piece of crap..
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