Steve - in the 14 bore single muzzleloader, with the .684" pure lead balls pathced with .022" denim, I used 165gr. GOEX. This gave me 1,550fps. I could not load WW balls with that charge with a cloth patch thick enough to withstand the pressure, but they did fine in paper ctgs., so were a second shot, 8 second reload proposition. A thinner patch and card wad might have worked but I never went there.
: In the 12 bore double ctg. gun, I used up to 191gr. (7 drams) of 2F GOEX with a .684" WW ball sitting in the inverted gas check off a trap wad. I protected the plastic from the black powder flame with a card wad. 191gr. gave 1,550fps with the small .685", 466gr. ball, as well as with a 545gr. .715" ball. I assume the heavier ball increased the burn rate of the powder slightly, giving identcial veloctiies as the smaller ball.
; With smokeless powders in modern ctg. guns, you can duplicate the 7 dram load with about 1/3 to 1/2 the recoil of black powder.
; Since you are talking muzzleloaders, the guys with the Pedersoli 12's are using up to 175gr. Swiss and getting 1,600fps or thereabouts with .715's. This is right around eqivalent to my ballistics in the 14 bore in that velocities were running about the same. I needed over 200gr. 2F GOEX to get 1,700fps. & that kicked too much.