In a 1927 Western Cartridge Co. flyer "Super-X The Long Range Load" Capt. Chas. Askins described the 12g. duck load as 1 1/4 oz. with 38 1/2 grains DuPont Oval with a muzzle velocity of 1400 fps (SAAMI standard is to measure at 3 feet from the muzzle) and "over a 40 yd course 1000 fps"; with a breech pressure of 3 3/4 tons (or 11,480 psi by Burrard; 11,172 psi if X 2240 X 1.33)



The 1931 pressure curve was still Tons



In 1933 PSI

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