From my research in old North American ammunition company catalogues, the heaviest 12-gauge loads offered from circa 1900 to 1921 were these, 3 1/2 drams of bulk smokeless powder pushing 1 1/4 ounce of shot --
and these with 28-grains of Ballistite dense smokeless powder pushing 1 1/4 ounce of shot --
According to some DuPont powder booklets in my collection by Wallace Coxe, one of their ballistic engineers, the 3 1/2 dram loads developed in the 11,600 to 11,700 pounds while the 28-grains of Ballistite was in the 12,600 range.
Threaded Mode