I loaded my round balls from Lee molds in my tumbler and ran it with a little soap and water for a while. It smoothed out the edges of the sprue cut and gave the whole ball smother appearance.
Decided that the gain (virtually none) was not worth the nasty inside of the tumbler and the dirty hands from handling the ball.
I don't do that anymore.
I do a lot of stuff like that for my own amusement and the remote possibility that they may help.
Like sanding the ears off of the grip on Piettas. No change seen.
Lowered hammers on Piettas. Very little change seen. Probably won't do them again.
457 round balls instead of 454s. Bad deal. Too much effort to seat.
Slix nipples which allow use of lighter main springs. Big change-I like.