In the 50's American Rifleman article from which that graph was taken (note it was re-produced for this article, was originally preparred by the DuPont labs in the 20's as I recall) it was stated that Black Powder had reached the peak of its effiency in the last decades of the 1800's. A lot of newer Black Powders are simply not up to the oplder powders. The quality of the charcoal used plays a large part in this as I understand it. Note the Elephant is consistently below the GOEX in both velocity & pressure. No data is listed here for Swiss, which is generally of a higher grade. The diference between the 2F & 3F would of course play a small part, but should not account for differences of any where near this magnitude.
