I see how many bullets meant for black powder use have large grease grooves. When using a bullet through a cap n ball pistol is this really necessary? It seems like a waste in a shorter barrel. Regardless, it seems as though the lube near the interior of the bullet would never even come into contact with the bore even through a rifle.
When shooting RB's through my Ruger Old Army I don't usually even bother with lubed wads any more.