The difference between the two powders is of course, pressure/velosity..If you are feeling you way here,I would start with 1f or canon grade. Work up a load from there.
Or, looking at shot gun loads, in drams..a black powder measurement, it would be simple to figure weight in gns to ounces, as in 1 1/4 ounce 20 guage, then apply the rule to your bullet weight of choice.
