Good synopsis there R'Mam. I would however point out a few things. DE (Drams Equivelent) was a term which came into being with Smokeless Powders, Black Powder was measured in actual Drams (1/16oz). The DE was used to designate an equivelent power (Velocity) not an equivelent pressure. Loading a 3 Dram load of black behind 1 1/8oz shot & a 3 DE load of say Schultze for a similar power level (1200fps) would not give the same max chamber pressure, as the Schultze was faster burning than the black. The early Bulk powders were measured to an equal "Volume" with Black of same power level, but not weight. DE came into use primarily beginning with the widespread use of "Dense" powders as both the Weight & Volume was difernt than black for a similar power level. Marking the shot weight was instituted I believe in 1896 on British proof for guns given the voluntary smokeless proof & both max powder charge wt (Smokeless, usually bulk) & shot wt were marked. This continued until 1925 at which time the actual powder wt was dropped & was simply marked Nitro & a shot wt. It was not until 1954 they upgraded to an actual pressure measurement, though Greener had spoken of the Crusher Gauge at least as early as 1911. The marking of the shot wt had led to some confusion among users as the suitability of a load was determined, not by actual shot wt, but by max pressure developed. Special low velocity loads for the 2½" gun had been developed using 1¼ oz shot but many felt using these "Took the Gun out of Proof", which was not the case. This situation was rectified with the 1954 Rules of Proof.
