2-piper, I'm glad you put the calculator to my numbers. In my haste I forgot to state that the cumulative grains were the total of both powder and shot (I have corrected the original post). Thanks for picking up on my mistake.
Here's a shortened table of the test protocol*:
1st proof 182 gr powder/729 gr shot=911 grains total
2nd proof 200 gr powder/802 gr shot=1002 "
3rd proof 220 gr powder/882 gr shot=1102 "
4th proof 242 gr powder/970 gr shot=1212 "
5th proof 256 gr powder/1018 gr shot=1274 "
6th proof 269 gr powder/1060 gr shot=1329 "
7th proof 282 gr powder/1122 gr shot=1404 "
8th proof 296 gr powder/1178 gr shot=1474 "
9th proof 310 gr powder/1236 gr shot=1546 "
All barrels were tapered the same but not chambered and were bored cylinder:
Breech .238
3 inches .150
6 inches .092
12 inches .048
21 inches .035
30 inches .048
The tests were later continued until either bursting or exhibiting a bulge equal to .01 of an inch, or an increase of from .729 to .739 diameters. The ranking changed considerably. The Whitworth steel dropped to third place with a cumulative average of 9,909 grains. The English machine forged laminated steel barrel in three rods dropped all the way to 32nd place, failing after an average of 6,738 grains. Only foreign barrels were lower. !
For those of us who love to shoot damascus guns here is a very important piece of information:
The Whitworth barrels withstood proportional stress of 10.88 times the standard Birmingham definitive proof. And the English laminated barrels held up 7.40 times the same definitive proof!!!! The very worst barrels tested were foreign twist and they withstood at least 5.74 times the Birmingham definitive proof before bursting or bulging!
*Data from Field Magazine, March 7, 1891, Vol 77, p.325
Last edited by Joe Wood; 10/31/10 05:09 PM.
