Bill may be correct. 42 gr. "Schultze" would be 3 Dr. Eq.
Forest & Stream, September 24, 1910 listed several standard British loads and pressures from
The Fieldhttps://books.google.com/books?id=mEkcAQAAMAAJ&pg=PA51042 gr. (3 Dr. Eq.) Schultze with 1 1/8 oz. shot = 9,598 psi (by Burrard’s conversion)
33 gr. (3 Dr. Eq.) “E.C.” Improved No. 3 with
1 1/16 oz. = 8,758 psi
33 gr. Smokeless Diamond with 1 1/16 oz. = 7,952 psi
33 gr. Red Star (New Explosives Co., Stowmarket) with 1 1/16 oz. = 8,322 psi
Major Sir Gerald Burrard in the 1944/1947 Second Edition of The
Modern Shotgun, Vol. III “The Gun and the Cartridge”, states during WWI the standard 12g load was dropped by law (to conserve the supplies of lead and powder) to 1 oz. 3 Dram.
After the war, the standard for 12g 2 1/2” shells became 1 1/16 oz. with 42 grains (Old) “Schultze” Bulk (3 Dram), 36 grains “E.C. No. 2 (Improved)” or 33 grains Imperial Chemical Industries (Eley & Kynoch Cartridges) “Smokeless Diamond” powder.
