A Hunter Arms Co. Pressure Curve dated June 10, 1929, is in the McCracken Research Library, Buffalo Bill Center of the West
http://library.centerofthewest.org/c...d/8149/rec/107
Maximum Standard Factory Loads 1” peak pressures
12g 3” ‘Record’ 1 3/8 oz. shot presumed 1275 – 1295 fps =
13,250 psi
12g 2 3/4” ‘Field’ 1 1/4 oz. shot presumed 1330 fps = 10,750 psi
12g 2 3/4” 1 1/4 oz. 28 gr. (3 1/2 Dr. Eq.) Ballistite =
12,900 psi
12g 2 3/4” 1 1/4 oz. 3 1/2 Dr. Eq. DuPont Bulk = 10,000 psi