How much does your rifle weigh, what is the weight of the projectile and when was the gun made? I see what your trying to do but without some period Curtis and Harvey's how can we compare Goex to Swiss to the 1880's vintage which we know to have been a stronger brew. Sometimes the use of 30gr per dram is what is needed to get proper velocity, at least with the 12's and larger. I use Swiss ffg in my big 10's and my 8's at 28 or 29gr per dram.