Curtis & Harvey T.S. (Treble Strong) was developed in 1871 for the .577/450 Boxer-Henry cartridge used in the Martini-Henry rifle. It was a precursor to R.F.G.2 (Rifled Fine Grain 2) manufactured at the Royal Gunpowder Mills, Essex, adopted in 1873.
C&H, "T.S." No. 6 (84 grain = 3 Dr. Eq.) was coarse Black Powder somewhat similar (but not equivalent) to Fg.
C&H, T.S. No. 4 (82 gr. = 3 Dr. Eq.) medium grain similar to FFg
C&H, T.S. No. 2 (72 gr. = 3 Dr. Eq.) fine grain similar to FFFg.
https://books.google.com/books?id=inQCAAAAYAAJ&pg=PA296&dq

1 1/8 oz 3 Dr. 12 gauge pressure was listed as 5820 psi + 10-14% for modern piezo transducer numbers
1 1/4 oz. 3 1/4 Dr. was 7790 psi + 10-14%

4 1/2 Drams 1 1/2 oz. is a BOOMER load even in a 10g




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