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
Yes Bill, I used the word inclusion very early in this "Mountain-Out-Of-A-Molehill" discussion.
Based upon the first pictures we saw, I was of the opinion that the burst initiated at the point of the dark spot, where the chamber wall was exceedingly thin, and it also appeared that the braze joint was compromised or defective. This was well before we saw any photo of the rear end of the blown shell. I felt that the dark spot was possibly an inclusion such as rolled-in scale, which unfortunately just happened to be in a spot that was machined very thin during the barrel jointing process. The same sort of inclusion hidden between the ribs and located much further down the barrels might have never been noticed.
I was ridiculed by the Preacher for making an observation based upon what was plain to see. And that observation did not include highly unlikely causes such as probable ring bulges, bore obstructions, or a shell that did not fully open at the mouth. Later, when Dewey Vicknair came to very similar conclusions with photos having
notations in red, that was perfectly acceptable, and Dewey was not similarly castigated, discredited, or taken to task for making a logical and rational observation based upon the evidence at hand.
But don't forget... I'm supposed to be the one with self-loathing, hatred, and acid in my soul... according to the Preacher.
I'm still not convinced that this was the result of some extreme overload. But we know that there was enough pressure to finally exploit this thin weak area that appeared to have an inclusion and compromised braze joint. It appears that there was a weak spot present ever since the gun was manufactured, and it quite possibly got worse over time. It takes a LOT of pressure to extrude a primer and get extractor imprints like that. But all bets are off with a shell case that is abruptly unsupported by a chamber that lets loose in those milliseconds when pressures are peaking.
Specifically, I'm thinking about a lot of burst steel tubing I saw a number of years ago when I spent a couple days working on a PLC program controlling high pressure pumps on a Hydrotester. Part of the problem was that pressures were unpredictably going way too high and bursting tubes that were not otherwise defective. I got to witness a lot of impressive bursts, and was close enough at times to get drenched when they ruptured. I was very surprised by they way the tubes reacted, even though pretty securely clamped into the machine. There was simply no predicting the result, and the ruptured tubes often twisted and cork-screwed weirdly. Of course Hydrotesting is pressure testing done using water instead of highly compressed air or a gas because a burst involving gas pressure would be much more violent and dangerous.
Thin plastic shell bodies and thin brass or brass plated steel shell heads can easily contain normal pressures when they are adequately supported. It's what they are designed to do. Abruptly take away roughly half of that chamber support in a burst like this, and I don't know how anyone can predict exactly how those thin materials would behave. Pretty near impossible to duplicate those same conditions to verify results as well.
Wear your shooting glasses. Keep your life insurance premiums paid. Avoid distractions while reloading. And enjoy shooting vintage doubles knowing you have a better chance getting injured or killed on the drive to the skeet range. Because no amount of anal hysteria or careful barrel wall thickness measuring was ever going to predict or prevent this burst... especially when done by someone who actually thought that lengthening chambers would result in GREATER WALL THICKNESS at the ends of the re-cut chambers. And maybe it would be good for the Preacher to take those measuring tools and carefully check himself for thin skin... not that it would help.
