Wish we knew Mike.
I believe Coxe reported the 3 1/2 Dram Eq. 1 1/4 oz. load pressures in
1928. Researcher would know
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
It is my
opinion that these are likely transducer numbers since 28 grains of Ballistite is already well over modern SAAMI 12g 2 3/4" and 3" maximum of 11,500.
I have the
1931 booklet in which this graph appears. "The vertical line represents the pressures developed by the various powders. This is measured in long tons (2240 pounds)."
It does not state HOW the pressures were measured however.
Charge was 1 1/4 oz. Dram eq. was not specified but was likely near Maximum. Using the estimated Lead Crusher Pressure (Cp) conversion to PSI (pound force per square inch) (Cp x 1.5) - .5 = TSI, TSI X 2240 = PSI.
Ballistite maximum pressure at 1” was 4.9 Long Tons = 15,344 psi
Schultze at 1 1/2” was 4.5 Long Tons = 14,000 psi
This graph appeared in the
1933 booklet and is PSI. I don't have a copy so can't say what technique was used but Miller and Bro. Larry debated this issue here not long ago.
DuPont MX Smokeless was a Dense Multi Base Powder introduced about 1930. 25.5 grains was a 3 Dram Eq. and it was promoted as a 1 1/4 oz. Trap load. It was replaced in the 1954 with IMR PB.
