The 1933 edition of Smokeless Shotgun Powders by Wallace Coxe and E.I. du Pont de Nemours & Co. reported the LUP pressure for 3 Dram Eq. with 1 1/4 oz. of DuPont bulk smokeless at 9,600 psi.
Coxe previously reported 3 1/2 Dram Eq. 1 1/4 oz. loads:
DuPont Bulk smokeless powder - 11,700 psi
Schultze Bulk smokeless powder - 11,800 psi
28 grains of Ballistite - 12,600 psi
40 grains of DuPont Oval Progressive Burning powder - 9,400 psi
In a 1927 Western Cartridge Co. flyer "Super-X The Long Range Load" by Capt. Chas. Askins the 12g duck load is described as 38 1/2 grains or 3 1/2 dram (powder not specified but likely DuPont Oval) with a breech pressure of 3 3/4 tons or 11,480 psi.
Drew,
Do we know whether they were aware of the disparity in the units and used a "fudge factor" to guesstimate psi, or did they just use the terms interchangeably at that time?
