YOu are wrong. Drag is based on shape of the projectile, not weight, or weight distribution. Its far easier to put a sprue UP when loading than to try to load it down. When YOu have more experience with MLing, you will understand that. Most casting flaws, like cavities, are so small that they don't adversely affect accuracy much for close range plinking and target shooting. It makes a big difference when shooting out at 100 yds and further. That is why balls are weighed, measured and visually examined before being chosen for serious target shooting.
The only way I know to make perfectly round balls is to put the cast balls in a case vibrator, or tumbler, without the grit used with modern cartridge casings, and let the lead balls bang around into each other for an hour or so. You will still need to measure then, and then weigh them,but you should find a lot more balls that are closer to being perfectly round, than you can expect to get out of any mold.
Since soft lead balls are distorted and mis-shapened when fired( and loaded), there is no point to making them "perfectly round". Its far more important for accuracy that they all weight close to the same weight. That is what produces small groups at your Point of Aim. :surrender: :hmm:
