Barrel proof

[jerrywh]

 The last barrel I proofed was a pistol barrel 10" long made of 1137 steel. The wall at the breech was .163 tapered to .032 for 6" and the .032 to the muzzle. The bore was 54 cal smooth.  I figured the standard load would be about 20 grs. Of 3F.
   I loaded it with 2 patched round balls and continued to increase the load 20 grs at a time until I reached 7 times the standard load. actually 150 grs of 3f. No sign of failure could be detected the barrel was measured at intervals of 3" after each load with a micrometer  and showed no deformities. Once I also proofed a fowler barrel with 600 grs of 2F and 3 oz. of #6 shot three times. No failure occurred. I still have that gun  i made it 1n 1974.
    Now. An old friend of mine use to make Blunderbusses about 30 years ago. He made the barrels from shelby so called seamless steel tubing. After making and proofing two of them the third one blew to pieces the first standard load. The barrels were heavy. The breech plug was intact. He never made another.   Go figure.

[jerrywh]

 The ID or his blunderbusses was 12 ga.  I don't remember the wall thickness at the breech but it was pretty thick. somewhere among my thousands of photo I have a photo of one of his.  Looking at it you would never think it would be unsafe. I made several barrels from seamless steel tubing and never had a problem. I proofed the heck out of them.
 I think his name was Jim Wolfred. He lived in Vancouver Washington at the timm. He is dead now. This was about 25 years ago.

[JTR]

The wall at the breech was .163 tapered to .032 for 6" and the .032 to the muzzle.

So the the wall of the breech was 163 thousands, then tapered down until the thickness of the barrel was 32 thousands of an inch, or 1/32 of an inch out the the muzzle?
I'm curious,,, is that correct?
John