We can even choose loads that reproduce the ballistics of the loads for which the guns were designed
DuPont Ballistic Table published in Parker Brothers' “The Small Bore Shotgun” c. 1920
http://parkerguns.org/pages/PDF%20Do...%20Shotgun.pdf
It is clear that this table converts Long Tons to PSI simply by multiplying by 2240; NOT using Burrard’s conversion
p. 7
“All powders referred to on these pages are of the bulk nitro kind ranging from 12 (“New Schultze”, New “E.C. Improved No. 2”) to 13 1/3 (original DuPont Bulk) grains per dram…”
Original “E.C.” and “Schultze” were 14 grains/dram
Numbers were measured by crushers and require adding 10 - 14% for modern piezo transducer pressures.
12 gauge
3 Dr. Eq. 1 1/8 oz. = 8,110 psi
3 1/4 Dr. Eq. 1 1/8 oz. = 8,960 psi
3 1/2 Dr. Eq. 1 1/4 oz. = 9,900 psi
16 gauge
2 3/4 Dr. Eq. 7/8 oz. = 7,035 psi
3 Dr. Eq. 1 oz. = 8,980 psi
20 gauge
2 1/2 Dr. Eq. 7/8 oz. =
12,655 psi (Modern SAAMI limit is 11,500 psi)
DENSE Smokeless Powder pressures would be 1000 - 1,500 psi higher