Re: .58 cal loads
A wad under a patched round ball does nothing to seal the bore. It is a simple matter of geometry. A bore size wad will be approximately 1/3 too small to seal the bore. The seal the bore, a wad would have to reach all around 1/2 the area of the ball. From where the ball meets the bore on one side to where the ball meets the bore on the other is pi x d divided by 2. so for a .490 ball, the wad would need to cover .769 inches round. a bore size wad, of .5 is .269 inches too small to seal the bore when pushed up against the ball by the force of ignition.
I have had several 58 caliber guns and to an extent the loads were much the same and to an extent they needed to be different to account for the different rifling. My smooth bore, shot well with 80 grains of 2fg and a .570 round ball and a heavy patch. .0025. My 58 half stock did well with 80 grains and a the same ball and a slightly thinner patch. In my Italian reproduction Zouave with only three grooves and progressive rifling, It did best with a .575 ball and a thin muslin patch of .005. I used 75 to 80 grains for all my 54 and 58 cal guns.