I shoot N-SSA competition.
If you are shooting for competition accuracy out of smoothbore muskets, many of the shooters are very particular about their ammunition preparation. They will take their .69 round balls and roll them between two plates of marble to get them perfectly round. Then they will roll the balls between some files to put some "tooth" on them, and then coat them with Lee Alox lube.
I don't have a smoothie, but one of my team mates has let me borrow his, and it is amazing to shoot. When you "ram" the ball down on the charge, it feels like an air piston the ball fit is so precise. The ramrod literally "bounces" on the air compressed under the ball.
For revolvers, I find the Lee mold makes small sprues. The sprue is less of a deformation than what the ram on my '58 does to the nose of the bullet during loading anyway. I suppose if you were really particular you could machine or put some JB Weld on the nose of the ram and set a round ball in it to set up so that when the ram drove the ball home it would make a perfect spherical impression onto the ball, obliterating any sprue remnants.
But I have read before that the bulk of your aerodynamic impact of your bullets comes not from the front of the bullet but the rear.