Theoretically 100 grains of pellets are 100 grains of loose 2F black powder or RS/Select. The Triple Seven Pellets are designed to provide the same "energy" as does the Pyrodex Pellet.
Loose Pyrodex 2F powder (RS) is very potent stuff nowadays and is almost as hot as is Pyrodex P (3F).
One has to experiment with powder to come up with what is best for his gun. The arbitrary guidline of 2F for 50 caliber and up is erroneous advice at best. Some smaller calibers shoot better with 2F than they do with 3F, which is recommended. The only way to really tell is to try it.
As for substituting 3F for 2F you need to work up your loads for optimum accuracy. There is another tale that suggests restricting your loads by 15% or more in comparison. With todays powders, that by itself won't really tell the tale. The best approach would be to have access to a chronograph and work your way up to similar velocity with the finer powder and start the process with maybe 60 grains of the finer powder. Like has been illustrated over the last year or so by a number of tests, Pyrodex P and RS are so close now in performance its hard to tell the difference except in the residue left behind.
When you get into Black Powder... 2F Swiss may not represent the same thing as 2F Goex. In all cases with powder, you need to operate with care.
Aloha...
