doublegunshop.com - home Forums General Discussion DoubleGun BBS @ doublegunshop.com Black powder and service pressures.

Here 'ya go Keith, since you "have no exact dates (sic - data?) at hand right now" and apparently couldn't find the time to locate it.

Sporting Guns and Gunpowders: Comprising a Selection from Reports of Experiments, and Other Articles Published in the “Field” Newspaper, Relative to Firearms and Explosives, 1897
http://books.google.com/books?id=inQCAAAAYAAJ
“Powder Pressures At Different Parts of the Gunbarrel”, 1895
https://books.google.com/books?id=inQCAAAAYAAJ&pg=PA32&dq

Black Powder Pressures for a service load of 3 Dram Eq. with 1 1/8 oz. #6 shot at 1220 fps



72 gr. C&H No. 2 T.S. (somewhat similar to FFFg) = 3.2 Tons = 9,632 psi (converted using Burrard's formula)
84 gr. C&H No. 6 T.S. (similar to Fg) = 2.1 Tons = 5,936 psi
82 Gr Curtis & Harvey’s No. 4 T.S. (similar to FFg)
Breech - 2.26 Tons = 6474 psi
2 1/2" - 1.96 Tons = 5466 psi
6” - 1.26 Tons = 3114 psi
12” - .9 Tons = 1904 psi
18” - .37 Tons
24” - .27 Tons



And as jones said, the British Proof House made no mention of service pressure until 1925; when the 12g barrel flats were marked with chamber length and 1 1/8 or 1 1/4 oz.
The 2 1/2” & 2 5/8” 12g maximum service load was reduced to 3 Dr. Eq. with 1 1/8 oz. shot with a mean pressure of 3 1/4 tons by LUP = 9,800 psi by Burrard’s conversion.
The 2 3/4” 12g max. service load was 3 3/8 Dr. Eq. with 1 1/4 oz. shot with a mean pressure of 3 1/2 tons = 10,640 psi by Burrard’s conversion.

I "have no exact dates or data" as to Black Powder proof after the 1925 revisions and since, but hopefully Keith will post his research.