From “Smokeless Shotgun Powders: Their Development, Composition and Ballistic Characteristics” by Wallace H Coxe; E.I. du Pont de Nemours & Co., 1927, a DuPont Oval Pamphlet, p.20.
Charge was 3 Dr. Eq. and 1 1/4 oz.
Pressure is expressed in Long Tons. sq/ inch but
it appears that PSI X 2240 was used to calculate those values (and maybe + 10-14% for modern transducer numbers)
Ballistite maximum pressure at 1” was 4.9 Long Tons = 10,976 psi
Schultze at 1 3/4” was 4.5 Long Tons = 10,080 psi
DuPont Bulk at 1 2/3” was 4.1 Long Tons = 9,184 psi
FFFg at 1 1/2” was 3.8 Long Tons = 8,512 psi
DuPont Oval at 2” was 3.5 Long Tons = 7,840 psi