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Joined: May 2010
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Drew,

Thank you for the great effort. This certainly is an interesting thread, in addition to the related others.

Your ...

"IF METAL FATIGUE IS PRESENT, microphotographs will show evidence thereof. Adam described it as the appearance of the sand at the edge of the shoreline ie. layers of wavy lines."

... was what I was referring to when I used the term "beach marks" early on.

When reading that the gun had sat around wet for a couple days I pretty much crumbled-up that paper (the thought of possible metal fatique from repeated firings of max loads) but I am still looking forward to seeing the microphotographs.

Thanks again,

Mark

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Drew,

This opportunity for testing is awesome! I'm glad that Adam told you that composition testing would require a larger sample. That is what I fully expected and why I was suspicious of the metallurgical testing company that told me they could provide results from patterned damascus. I feel good about who you are working with.

It's very hard to do an accurate visual examination of the barrel metal through the photos. But, I keep looking at the grain structure of the steel along the broken edges. It appears to be of very large grain size. Large grain size in steel looks like sugar crystals. Small grain has a dull, gray appearance. If the grain is large, this would suggest that the steel was not thermal cycled enough and/or properly to reduce the grain size after forge welding. Large grain would not be terribly surprising. As I discussed in another thread, the barrel smiths knew that cold hammering improved the steel, but did not fully understand that it was the repeated heating and air cooling (thermal cycling) of the steel that caused a reduction in the grain size. The degree that the barrels were cold hammered, varied by the quality of the barrels. Too, the smith's skill at heating the barrels properly for grain reduction was surely a factor.

Large grain in the steel will weaken the steel slightly, but should not be considered a major defect or weakness. Though if embrittlement occurs, it would most likely begin in an area of large grain size, vs. small grain.

Photomicrograph examination will be very interesting. I think you may be amazed at how clean the steel is. I suspect that only a few very small slag inclusions will be found.

If composition testing of some demonstration rod material becomes a possibility, I might be bold enough to post up a prediction of what will be found. I'm fairly confident in what I believe to be the major alloys in the two materials. I haven't had time to do the research that I hope will help to determine the trace alloys. Let me know if you get some samples to test and I'll try to get my research done. I may end up looking like a fool, but I think it would be fun to see if my research is accurate.


Steve Culver
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I would expect, in the case of an obstruction, that the barrel would have blown just prior to that obstruction. I still lean towards an overloaded cartridge theory. I still think it may be worthwhile sending the photographs by e-mail to the Birmingham Proof House and seeing what their theory is. I'm sure they will have either seen it before or created it with their lab experiments. There's 200 years of experience there at the click of a mouse. At the very least they should be able to narrow down the search field. Lagopus.....

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I still cling to the belief there was an obstruction. The exact location of a burst in relation to said obstruction is also related on how much the obstruction moved upon being hit. If it was solid & unmovable then the burst would have been behind it. In the case of a movable obstruction the burst may actually come forward of where the obstruction initially was, the amount dependant upon the resistance of the obstruction. Another thing to consider also is that at this point in the barrel the inner wall is supported by the other barrel, the point to where they become separated has not been reached. Consequently I do not see it as unusual the bulge was confined to the outer wall.


Miller/TN
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I have nothing constructive to say, but what you do is amazing. Wanna save both threads, along with whatever's forthcoming, and study it carefully. My compliments!

2-piper #357227 02/11/14 01:04 PM
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Sidelock
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Originally Posted By: 2-piper
....In the case of a movable obstruction the burst may actually come forward of where the obstruction initially was, the amount dependant upon the resistance of the obstruction. Another thing to consider also is that at this point in the barrel the inner wall is supported by the other barrel, the point to where they become separated has not been reached. Consequently I do not see it as unusual the bulge was confined to the outer wall.


I seems to be possible. I think I can see machining, honing?, marks just opposite the bulge, they appear crisp and unaffected by the pressure it might have taken to the blowout in the other direction. It seems like in the chamber maybe about mid hull the scratch pattern is smooth and it seems like the measurements say the chamber may be bulged back by the case head.

I wonder if the pressure spike was actually in the chamber and too high, or built at too quick a rate, for the metal to deform. Maybe at the bulge the pressure was dropping to allow the metal to act in a plastic way. I think the picture of the monosteel blowout in part 2 on Feb. the 5th. shows similar, but may also be more of a 360* bulge.

Thanks again Doc Drew for digging deeper. Maybe back to the reloads you took apart, you could tell something about the depth of crimp or possible primer substitution. Could be a moving obstruction from a load that pressure spiked and the old Remington just had enough of. I've wonder if Tony T's barrel crack right out of proof would have looked similar if someone had put a few more rounds through it.

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Craig, in your last paragraph about the depth of the crimp or possible primer substitution, Joe Wood loaded that exact recipe but doubled the powder and if you look at his post with the picture you will see it did not or could not crimp.
Also unless it was a magnum primer such as a Federal 209M or CCI 209M the increase would not be substantial.

I posted on Shotgun World on the Reloading Forum and received many response about dropping a double charge in Mec Progressive machine.
Some said yes, but one poster said this "Powder does not fill the bar of a MEC until the bar goes fully left, it drops the powder when it travels toward the right.".
If there was a powder bridge in the tube, the shot would not have fallen in the previous load, or everything would have fallen.

With most of these newer components, there is minimal wad pressure, mostly less than 20 lbs. If there was a double charge of powder and IF the shell crimped the wad legs would be crushed and you would have to use close to 100 lbs. wad pressure, but you would see that before hand.


David


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Drew,

I will be very interested to find out what you see via x-ray.

I had x-ray and magna-flux work done on a handful of barrel sets 20-25 yrs ago. My own experience was that neither process was definitive. A couple of tubes had pitting and I would have thought that something besides just the puts would have shown on those, but no. Advances have been made in x-ray technology, and hopefully you will gain more insight today.

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Postscript to the above - they were all Damascus barrels.

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Drew,
I've sent the links to Peter Powell at the Birmingham Proof House.

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