60947 Fires it's last shot

[Ed Blake]

Wow! Look at those chamber walls and how they have been stretched. You say Gunter Pfrommer ID'd a crack in the chamber wall after the kaboom and it is still visable? I can't see it. Glad you are OK.

[John Truitt]

Like Dean said Dr Dreu Hause is investigating a very similar issue on another Damascus gun. Very similar.

Contact Dreu or atleast check out the double gun website.

I hope you were not hurt. I am sorry this happened to you.

Please keep us informed if you do figure out the cause.

Was the thought metal fatigue due to the crack, obstruction, over pressure/ over load?

[Drew Hause]

David: I'm thankful you were not seriously injured.
As mentioned, right now METL here in Phoenix is finishing a formal failure analysis of a chamber blow out http://metl.com/services/
The 3 threads on DoubleGun
http://www.doublegunshop.com/forums/...=356377&page=1
http://www.doublegunshop.com/forums/...999#Post354999
http://www.doublegunshop.com/forums/...=357105&page=1

By the appearance of the blow out, I think there is little doubt that there was an obstruction, likely at the forcing cone, and would suggest that you examine every empty used prior to the event for a missing base wad or piece of plastic. AND please check the shell that was in the chamber for expansion of the head, and an indentation on the head from the extractor. Because of the plastic deformation of the chamber, I am quite confident that this was not simply a fracture of the barrel wall.

A formal failure analysis costs more than $1000, but if you would like to send me the remains, I could measure the wall thickness around the blow out and also ask the Metallurgical Engineer at METL for his opinion. Possibly a visual exam of the edges would confirm my thoughts.
Also please send the remnants of the shell, or post an image of the head.
Another option would be destructive testing of the remains, with sectioning and photomicrographs. This is the big $s.

BTW: I'll add your images here, with an attribution
http://www.picturetrail.com/sfx/album/view/24513874

Feel free to contact me at drewhausemd@yahoo.com if you'd like to discuss further testing.
Drew Hause M.D.

[David Noble]

I wonder if these recent blowups have occurred due to detonation. Seems most if not all of these that were not the result of an obstruction were "lite" or reduced load reloads. Detonation occurs when there is too much space in the powder compartment and the powder burns instantaneously instead of progressively causing a huge pressure spike. It seems feasible that the wad in these reduced loads is not compressing the powder adequately?
Just a thought.

[Parker Bachelder (Brad's Profile)]

David

It is a blessing that no one was hurt in this accident. You are fortunate this did not occur with fluid steel barrels. Yes I am defending Damascus.
Without the gun in hand for testing, I can't make any definative statements, however, I can offer a cursory opinion. Only two things can cause this type of failure. An extremely over pressure shell or a rigid obstruction at the forcing cone. This type of ripping of the metal indicates a single event failure, not a mechanical or structural problem.
When fliud steel barrels are exposed this type of pressure they will usually demonstrate longitudinal cracking and more fragmentation with little or no bulging. The photos show considerable bulging prior to the metal shearing off. This attests to certain maleable property I have only seen in compostie steel Barrels. A lot less shrapnell and a more gradual release of pressure.
The stock breakage is due to gases escaping into the receiver via the firing pin hole.
The beautiful patterns are not the only reason that Damascus Barrels were considered Premium.

Brad