Quote:
Originally Posted by Drew Hause
1 1/4 oz. with 3 1/2 Dr. Eq. was the standard Live Bird load in the U.S. 1895 - about 1900; and although Krupp, Siemens-Martin and Whitworth fluid steel barrels were available, certainly most guns were Damascus
Sporting Guns and Gunpowders, “Tests Of Strain On Breech Actions”, in Field, 1892
1 1/4 oz. 3 1/2 Dram Bulk Smokeless Pressures in 2 3/4” case
https://books.google.com/books?id=inQCAAAAYAAJ&pg=PA86
Long Tons/ sq. inch converted to PSI by Burrard’s formula
(Proof) with 6 1/4 Drams “Tower Proof” Black Powder and 1 2/3 oz. shot – 4.51 Tons = 14,034 psi
3 1/2 Drams Curtis & Harvey’s No. 4 T.S. Black Powder – 4.2 Tons = 12,992 psi
“Schultze” – 4.28 Tons = 13,260 psi
(In a 3” case, with additional wadding the pressure for “Schultze” was 4.93 = 15,445 psi )
“E.C.” – 4.92 Tons = 15,411 psi
Note the SAAMI 2 3/4" 12g Max. is 11,500 psi
and BTW 1 1/4 oz. 3 1/2 Dr. Eq. (1275 fps) in an 8# gun = 27 ft/lbs free recoil 
1 1/8 oz. at 1200 fps in today's 10# trap guns = 16.2 ft/lbs |
Drew, not to get anything started here again but I read that you're using "Burrard's conversion" factor to come up with those psi numbers. Can you please elaborate how that conversion relates/applies to period
American lead crusher pressures, and from there to modern transducer measurement? Thank you.
Interesting that Askins wrote extensively in 1929 about American shotshell loading and pressure testing and although I read his volume many times I don't remember seeing any reference to Burrard nor anything other than lead crusher pressure in tons per sq inch. Let's take just one number from his chart for maximum loads of DuPont's Bulk smokeless as provided by its Brandywine Lab, i.e., 12-gauge 1-1/4 ounce and 3-1/2 drams shows an average of 4.70 tons. Now, correlating with the data here
in the quote that would be about 14,750 psi. That doesn't make sense to me