doublegunshop.com - home Forums General Discussion DoubleGun BBS @ doublegunshop.com Wall thickness opinion

Found this thread from 2013 which is not quite the topic
https://doublegunshop.com/forums/ubbthreads.php?ubb=showflat&Number=334038&page=1

Miller and Jack made the point that lower chamber pressures (for equivalent weight and fps) were attained using slower burning powders ie Red Dot to Green Dot to Blue Dot. But by doing so the pressure would be slightly higher further down the barrel.

Obviously computer generated illustration from an old Alliant resource



DuPont Oval was a progressive-burning "controlled combustion" smokeless shotgun powder developed for the Western Super-X loads.
This is 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 (+ 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
BUT the pressure generated by Oval at 4 - 6" was higher than the other powders.
At 4 1/2" Oval was about 3 Long Tons = 6729 psi and the others were about 2.5 Tons = 5600 psi (+ 10 - 14%)
I'm not a ballistic or mechanical engineer to know if that matters.