doublegunshop.com - home Forums General Discussion DoubleGun BBS @ doublegunshop.com Damascus gun blow up in Md last weekend?

Was hoping for more information, or the barrels, but neither has been forthcoming. It's the owner's gun, and he of course may do what he wishes with the remains.
It is frustrating however for those who use our pattern welded barreled vintage doubles to see reports of a burst, receive limited information and images, we all contribute not especially helpful opinions, and then have no definitive answer as to the cause; which could possibly be established as simply as measuring the wall thicknesses. Knowledge IS safety.

And re: the Parker top rib extension. This shows the screw head clearly, and mismatched Parker D4

wonderful photography...

I've been in contact with the gun's owner and, with his permission, hope to post more definitive information next week. The point is not to criticize anyone, but to learn what happen so similar events can be avoided.

The critical information we need:
1. Exact chamber length
2. Exact chamber dimensions (for evidence of previous honing). The entrance to the chambers of c. 1900 12g U.S. doubles is usually .809� -.812�, tapering to .795� - .798�.
3. Exact bore dimensions (for evidence of previous honing)
4. Minimal wall thickness at the end of the chamber
5. Minimal wall thickness at the forcing cone
6. Minimal wall thickness around the burst edges



7. Does the burst barrel appear to have a �ring bulge�?
8. Was the load confirmed to be factory? Which Remington Nitro load? If not, what was the reload recipe and the expertise of the reloader?
9. Is there visual evidence of over-pressure on the remains of the shell? Extractor imprint on the brass? Cratered primer?
10. Did the shooter notice anything abnormal the previous shot through the burst barrel? Sound? Recoil?

Certainly looks to have found the thin/weakest spot to blow.
How do you generally feel about 0.019 thickness. or should that be thinness ?
O.M

That tube shows significant distortion. There's a good chance that it was thicker than .019" before the mishap.

To clarify gentlemen, that image is an example of the measurements that need to be taken, from ANOTHER burst.
Craig's observation is correct, and I've discussed the issue with a mechanical engineer. That degree of elastic deformation is unlikely to thin the barrel more than .001 - .002".

For those with the interest, and smarts

Calculation of the tube thickness reduction rate

Wt = ( D-d0 ) - ( H - d1 ) / ( D - d0 ) � 100
d1 = (D-d0)�(1-Wt / 100)

Wt: tube thickness reduction rate (%)
H: sheet hole diameter before tube expansion (mm)
D: outer diameter of tube before tube expansion (mm)
d0: inner diameter of tube before expansion (mm)
d1: inner diameter of tube after tube expansion (mm)

And yes, .020" just past the forend (where the leading hand rests) is too thin.
CIP suggests .030" at 12", for 4140 strength steel.

Mr. Hause, Sir. I really appreciate your efforts to add to our collective knowledge. People like you are invaluable to the internet. Bravo.

Only a thought Doc Drew. These blow ups appear to be very asymmetrical expansions of a barrel tube. There also may be signs, such as refinishing, that point to an uneven wall thickness before the expansion occurs. Maybe it's a bit like blowing up a balloon with a thin spot and the shape distorts out of that spot. Hat's off to you for the great detective work.

Keep up the good work, Doc!