Western Cartridge Co. never marked the Super-X ‘Field’ or ‘Record’ boxes with “Dr. Eq.” stating only “Maximum Load”. It is presumed that 12g ‘Super-X Field’ 2 3/4” 1 1/4 oz. was 3 3/4 Drams Equiv. or 1330 fps, and the 3” 1 3/8 oz. ‘Record’ was 1275 - 1295 fps (the speed of 1 1/4 oz. 3 1/2 Dr. Eq. loads).
In a 1927 Western Cartridge Co. flyer “Super-X The Long Range Load” by Capt. Chas. Askins the 12g “Duck Load” (not specified but presumed to be 1 1/4 oz. Super-X “Field”) is described as 3 1/2 dram (38.5 gr. Powder; also not specified but no doubt DuPont Oval) #4 shot at 1400 fps (at the muzzle rather than 3 feet) and 1000 fps at 40 yards, with a breech pressure of 3 3/4 tons or about 11,480 psi by Burrard’s conversion.
From the 1928 edition of “Smokeless Shotgun Powders” by Wallace Coxe, ballistic engineer of the Burnside Laboratory of the E.I. du Pont de Nemours & Co.
3 1/2 Dram Eq. 1 1/4 oz. presumed #6 shot loads (1275 fps) and 40 yard fps:
NOTE: pressures were measured by crushers (LUP) and modern transducer measurement pressures would be 10 – 14% higher
DuPont Bulk smokeless powder - 11,700 psi, 943 fps
Schultze Bulk smokeless powder - 11,800 psi, 941 fps
28 grains of Ballistite Dense smokeless powder - 12,600 psi, 966 fps
All 3 are greater than the SAAMI 12g 2 3/4” recommended maximum pressure of 11,500 psi.
40 grains of DuPont Oval Progressive Burning powder - 9,400 psi, 981 fps
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