In my guns, MaxiBalls were basically a slip fit until the forward band contacted the rifling. Then it needs a little force to get that band into the barrel. After that, they slide down pretty easily. Even the MaxiBall design obturates a bit upon firing, before it heads down the bore.

I pre-size FPBs for my Genesis by pushing them nose-first down the bore and out the breech. They then load easily with fingers and just slide on down the bore with little pressure. I make sure to seat them with firm pressure once they contact the Pyrodex charge. Pyrodex likes to be compressed.