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Very well. You do know the movie.

Chuck, given the case head expansion into the extractor groove, I'd guess someplace north of 40K PSI.

That's a steel head on those shells, and they are noticeably harder to resize than brass heads.


"The price of good shotgunnery is constant practice" - Fred Kimble
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My SWAG is well in excess of 15K psi. Say 25,000 psi.

1) I base this on my estimation of the strength of the Damascus being around 60,000 psi ultimate, providing for mild steel being around 64,000 psi, and ductile iron being around 60,000 psi and some conservatism.

2) I used .100 as the Min Wall

3) A hoop calculation of a .798 I.D. chamber and .100 wall with a 60,000 psi strength is around 15,000 psi.

However, you can see the chamber wall is much thicker at the rear. Of course, my math could be all wrong too.

Last edited by Chuck H; 02/12/14 12:15 AM.
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Originally Posted By: Dave in Maine
Been following these threads with some interest and have to say this is some of the best forensic detective work I've seen in a long, long time. Y'all are to be congratulated and encouraged for it.

Now for my $0.02. I believe the consensus has coalesced around there having been an obstruction in the barrel. I recall part of the early discussion being that there was snow in the area when the gun was dropped after the blowout. Could the obstruction, which seems to have been the cause, have been snow itself?

Getting a clot of snow in the barrels is something I'm always watching out for while hunting in winter conditions. It has happened to me - thankfully I caught it before firing - and I can say it does happen without even noticing it.


I've seen lots of barrels bulged or even blown because of snow obstruction - quite a common occurence over here - and I don't believe this is the case.

The snow-caused damage invariably happens either before the choke, or mid-barrel where the barrel walls are the thinnest.

As a matter of fact, not all snow obstruction does damage to barrels (that's why it's so common - people get to be careless). The light, christmass-card-flakes sort of snow hardly ever does any harm. It takes heavy, wet snow to get the job done.

In order to blow the barrels in the chamber area, it would have to take a whole lot of wet snow somehow working its way to the chamber area and freezing in place there.

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Originally Posted By: Dave in Maine

Could the obstruction, which seems to have been the cause, have been snow itself?



i have seen barrels damaged from snow- the damage was at the muzzles, i would expect that to be the norm for that

Last edited by OH Osthaus; 02/12/14 08:14 AM.
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I asked METL to proceed with a formal failure analysis, and here's the estimate frown

Per your request the following quotation is for testing of the component submitted to determine the root cause of failure. Testing is to include preparation, analysis, examinations, photographs, and report.

Misc. sectioning and preparation of the sample: $40.00
Photomacro/micrographs (15 estimated at $15.00 each): $225.00
Metallographic mount and preparation (2 estimated): $105.00
SEM/EDX examination of fracture surfaces: $175.00
Metallographic Examination – Including metallographic examination, failure analysis, and full written report documenting all findings: $630.00

And some other stuff. Could buy a decent 16g shooter instead frown

The good news is that 3 articles will probably come out of all this, with the remote possibility that someone might pay me for the information:
A Blow-Up Post-Mortem
Damascus Mythology and Reality
Non-Destructive Testing of Damascus Barrels
Not sure what would be the best forum; possibly American Rifleman?

The next part of all this is to explore with Team Industrial Services here in Phoenix either MPI or (Adam's advice) radiography to identify wall defects. I will have:
The blown out 2 Iron Remington barrels
2 Iron Smith barrels
Chain Smith barrels
Damascus-Twist Ithaca barrels
and possibly a JABC Twist barrel.
The Ithaca barrels are unusable, so if a defect is seen, METL could then section the barrel and identify exactly the nature of the defect. I would also expect the different patterns to be apparent on x-ray?

I don't believe TEAM is a charitable organization either, but it's all in the name of science smile
and so far my long-suffering spouse is buying it.

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as for a venue - I doubt you would find a more interested audience than either DGJ or Shooting Sportsman

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To be clear the information above is not a solicitation for donations to the barrel testing cause. Please see my post in Misfires.

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For the service that seems to be presented, the cost looks to be very reasonable. Maybe a nondestructive testing recommendation at a fraction of the cost could come of it. You may, but I don't think, you'd see much of the damascus pattern on an xray. If the alloy components that cause the different colors are able to be distinguished by xray, I think the image would be muddied because it likely lays at random diagonals through a section of barrel. As you noticed though, most of the defects do not seem to follow the damascus patterns.

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MORE PROGRESS for Part 3 of this quest smile

I'll be meeting with the NDT manager at Team Industrial Services and will take a barrel donated by a fella here which is a candidate for destructive testing related to over-honing. Decided to do BOTH MPI (first) then radiography to compare the sensitivity for identifying wall defects (hope there is one!)
The cost is $125 for each test. If a defect is found, THEN METL can section the barrel and identify the nature of the defect.

TEAM has international offices and is throughout the U.S.
http://www.teamindustrialservices.com/

IF radiography (which is certainly interpreter dependent) turns out to be both sensitive (if it's there, it's there ie. no false negatives) and specific (if it's not there, it's not there ie. no false positives) that might be a helpful NDT for $125.

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Originally Posted By: Humpty Dumpty
Originally Posted By: Dave in Maine
Been following these threads with some interest and have to say this is some of the best forensic detective work I've seen in a long, long time. Y'all are to be congratulated and encouraged for it.

Now for my $0.02. I believe the consensus has coalesced around there having been an obstruction in the barrel. I recall part of the early discussion being that there was snow in the area when the gun was dropped after the blowout. Could the obstruction, which seems to have been the cause, have been snow itself?

Getting a clot of snow in the barrels is something I'm always watching out for while hunting in winter conditions. It has happened to me - thankfully I caught it before firing - and I can say it does happen without even noticing it.


I've seen lots of barrels bulged or even blown because of snow obstruction - quite a common occurence over here - and I don't believe this is the case.

The snow-caused damage invariably happens either before the choke, or mid-barrel where the barrel walls are the thinnest.

As a matter of fact, not all snow obstruction does damage to barrels (that's why it's so common - people get to be careless). The light, christmass-card-flakes sort of snow hardly ever does any harm. It takes heavy, wet snow to get the job done.

In order to blow the barrels in the chamber area, it would have to take a whole lot of wet snow somehow working its way to the chamber area and freezing in place there.


and
Originally Posted By: OH Osthaus

i have seen barrels damaged from snow- the damage was at the muzzles, i would expect that to be the norm for that



Good to know this - your answers exclude one possible source of the obstruction problem here.

Last edited by Dave in Maine; 02/12/14 11:30 PM.

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