Sorry to resurrect this old thread but this might help. The gun in question is from 1896 so the grains would be for the old "E.C." at 14 grains/dram.
"1895 Smokeless Powders For Shotguns"
http://books.google.com/books?id=Wv0MAQAAIAAJ&pg=PA446&lpg3 1/4 Dram/40 grains DuPont Bulk Smokeless 1 1/8 oz. = 7440 LUP
3 1/4 Dram/44 grains “E.C.” Bulk Smokeless 1 1/8 oz. = 7584 LUP
Of course by modern piezo transducers the psi would be closer to 8500.
Courtesy of Researcher from 1903
3 Dr. Eq. 1 1/8 oz. ‘Trap’ load recommendations:
New Schultze & New “E.C.” Bulk Smokeless - 33 grains (12 grains/drachm)
Old Schultze & “E.C.” No. 1 Bulk Smokeless - 39 grains (14 grains/drachm)
DuPont Bulk Smokeless - 36 1/2 grains
Hazard Bulk Smokeless - 3 Dram
The 1933 edition of ”Smokeless Shotgun Powders” by Wallace Coxe and E.I. du Pont de Nemours & Co. reported the LUP pressure for 1 1/4 oz. 3 Dram Eq. of DuPont bulk smokeless at 9,600 psi.
3 1/2 Dram Eq. 1 1/4 oz. load:
DuPont bulk smokeless powder - 11,700 psi
Schultze bulk smokeless powder - 11,800 psi
Pressures were determined by lead crushers and modern piezoelectric transducer measurements would be about 1000 psi higher.
