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Sidelock
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Reference has been made to "The Southern" chamber burst and failure analysis. I couldn't add to the old thread, and some may have missed it, so here 'tis
https://www.doublegunshop.com/forums/ubbthreads.php?ubb=showflat&Number=546106

There is no new information to share; specifically the recipe of the reload.
The diagnosis of the defect was made immediately by Dewey Vicknair, but I at least learned a great deal from the metallurgical study. There were several emails exchanged with both the metallurgist and metallurgical engineer to help me understand the results. The relevant snippets are in the thread.

I would be happy to send anyone interested the report from METL - it is a 5MB PDF.
Send me an email at drewhausemd@yahoo.com and please include in the body of the email the statement "I acknowledge this document is the property of Drew Hause. Nothing in the contents will be reproduced or shared." I'll reply with the PDF as an attachment.
Sorry, but I don't want to find an internet article somewhere with the study I paid for, and which may be misrepresented.

And BTW: I should get the Winchester Nickel Steel barrel to METL next week for composition analysis and tensile testing.
The tube is ruptured and I might also have METL prepare a micrograph of the burst edge. An obstruction with high pressure failure (above ultimate tensile strength) should show elastic [this is an error - it should be "plastic'] deformation with terminal cleavage. Low cycle fatigue failure (repetitive stress above the yield strength) has a different appearance. Might be interesting if not educational.

Last edited by Drew Hause; 01/18/20 04:17 PM. Reason: correction
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Originally Posted By: Drew Hause
....An obstruction with high pressure failure (above ultimate tensile strength) should show elastic deformation with terminal cleavage....

Only asking Doc Drew, is "elastic" a typo as far as being able to be seen at some later point?

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Sidelock
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Thank you Craig. Yes, the deformation should be "plastic" ie. not reversible

Cleavage cavity with ductile dimples. No low-cycle fatigue striations.


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Thanks much Doc Drew.

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I truly appreciate the time you take focusing and sharing


Michael Dittamo
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Thanks for the update - so the undisturbed conclusion is that the burst was the result of an original factory manufacturing defect?

I guess it is remarkable it held up as long as it did if that is the case.

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Dan: I should have linked the summary, without the extraneous verbiage, starting about 1/2 way down here
https://docs.google.com/document/d/1ZnptAPvQIlWG5n5UU2FmKcFpYtVmOSc4b7K7G9IBs4g/edit

My opinion was that the barrel failed because of the critical juncture of 3 factors:
An over-pressure (re)load.
A defective braze of the top rib extension wedge to barrel.
Inclusions (possibly a large inclusion) in the barrel wall.

The barrel did not fail because of low cycle metal fatigue.

A 2 3/4" shell in a 2 9/16" chamber may have been a contributing factor.

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Thanks for the clarification, Drew. Any idea what the approximate PSI on the reload was?

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Unfortunately no Dan. The shooter apparently did not have his reloads tested.
We do know that independent testing of those Cheddite for Herters 16g “Select Field Dove and Quail” 1 oz. at 1165 fps showed pressure averaging 12,500 psi, with one at 13,400 psi. Raise the pressure with the short chamber and we are approaching proof load pressures. WOW.
CIP standard for both 65 and 70 mm 16g is SERVICE 780 BAR or 11,313 psi; PROOF 980 BAR or 14,214 psi.


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So, how does a large company like Cheddite screw up that badly?

I still have a few flats of that load in stock and all the boxes wear the CIP certification.

My gut feeling is that they are mild loads. I've seen no signs of over pressure, and I've used perhaps a dozen flats of them.

For a steel head shell they extract easily and show no primer signs of high pressure whatever.

My BS indicator is wiggling on this 'independent' testing.

I have an honest interest in this subject Drew, I'm not discounting your second hand information but it does not add up in my opinion.


"The price of good shotgunnery is constant practice" - Fred Kimble
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