To summarize, maybe once and for all
Pressure expressed as (long) Tons/sq. inch as measured by lead crushers (LUP) may be converted to modern piezoelectric transducer PSI using Burrards formula
(Cp x 1.5) - .5 = TSI, TSI X 2240 = PSI
Pressure originally expressed a PSI (pound force per square inch) as measured by lead crushers (LUP) requires multiplying by 10 14% to reproduce pressure as measured by modern transducers
It appears likely that Wallace H Coxe, ballistic engineer of the Burnside Laboratory of the E.I. du Pont de Nemours & Co., used a PSI Tarage Table (for LUP) and simply multiplied by 2240 for Tons. This would also require multiplying by 10 14% to reproduced pressure as measured by modern transducers
SUMMARY OF REPORTED PRESSURES for 3 Dram Eq. 1 1/8 oz. Bulk Smokeless Powders3 Drams of DuPont FFFg (82 grains) is about 5000 psi.
3 Drams Curtis & Harveys No. 4 T.S. (82 grains; somewhat similar but not equivalent to medium grain FFg) was about 6500 psi.
Sporting Guns and Gunpowders: Comprising a Selection from Reports of Experiments, and Other Articles Published in the "Field" Newspaper, Relative to Firearms and Explosives, Volumes 1-2,
1897Powder Pressures at Different Parts of the Gunbarrel
https://books.google.com/books?id=inQCAAAAYAAJ&pg=PA32&dq 42 Gr Schultze - 1.69 Tons = 4558 psi by Burrards conversion
https://books.google.com/books?id=inQCAAAAYAAJ&pg=PA296&dqE.C. 5,830
expressed as psi + 10% = 6,400 psi
Schultze 6,110 psi + 10% = 6,700 psi
https://books.google.com/books?id=inQCAAAAYAAJ&pg=PA325 42 gr. Bulk (3 Dr. Eq.) 2.07 tons = 5,835 psi by Burrards conversion
G.T. Teasdale-Buckell,
Experts on Guns and Shooting,
1900https://books.google.com/books?id=P7UrAAAAYAAJ&pg=PA2351 1/8 oz. 42 gr. = 3 Dram Bulk Nitro 2.71 Tons = 7,985 psi by Burrards conversion
Forest & Stream, September 24,
1910 from
The Fieldhttps://books.google.com/books?id=mEkcAQAAMAAJ&pg=PA51042 gr. (3 Dr. Eq.) Schultze 1 1/8 oz. 3.19 Tons = 9,598 psi by Burrards conversion
William Bruette,
Guncraft: Guns, Ammunition, Wing & Trap Shooting,
1912 https://books.google.com/books?id=5g51K93as84C&pg=PA209&dqCurtis & Harveys (42 gr. = 3 Dram) Amberite
12g 2 1/2 case 42 gr. (3 Dram) 1 1/8 oz. - 3.0 Tons = 8,960 psi by Burrards conversion
Curtis & Harveys Smokeless Diamond (33 gr. = 3 Dram)
12g 2 1/2 case 33 gr. (3 Dram) 1 1/8 oz. - 3.2 Tons = 9,632 psi by Burrards conversion
DuPont Bulk Ballistic Table
c. 1920 3.62 Tons X 2240 - 8,110 psi + 10% = 8,900 psi (11,040 by Burrards conversion and obviously not accurate)
http://parkerguns.org/pages/PDF%20Documents/Small%20Bore%20Shotgun.pdf For ComparisonWinchester Factory Memorandum dated February 6,
190012g 2 5/8 Leader case, 1 1/8 oz. with 40 gr. DuPont Bulk = 3 1/4 Dr. Eq. - 3.9 Tons X 2240 = 8736 psi X 10% = 9,600 psi
The c. 1920 DuPont Ballistic Table listed that load as 4.0 tons X 2240 + 10% = 9,850 psi
Smokeless Shotgun Powders: Their Development, Composition and Ballistic Characteristics by Wallace H Coxe; ballistic engineer of the Burnside Laboratory of the E.I. du Pont de Nemours & Co.,
1927 Charge was
1 1/4 oz. 3 Dr. Eq.
Schultze - 4.5 Tons X 2240 = 10,080 psi + 10% = 11,100 psi
DuPont Bulk - 4.1
Tons X 2240 = 9,184 psi + 10% =
10,100 psi The 1933 edition of Smokeless Shotgun Powders by Wallace Coxe
1 1/4 oz. 3 Dr. Eq. DuPont Bulk - 9,600
psi by LUP + 10% =
10,500 psiModern
Dense Smokeless Powders in the Alliant 12g Reloading Guide
http://www.alliantpowder.com/reloaders/RecipeList.aspx?gauge=12>ypeid=31 1/8 oz. at 1200 fps (3 Dr.Eq.) in Winchester AA case, Win 209 primer & WAA wad
Unique (Infallible) 21 gr = 9,100 psi
Green Dot 19.5 gr = 9,300 psi
e3 17 gr = 10,450 psi
Red Dot 18 gr = 10,400 psi