I used a Lee bottom pour lead pot for years, Cast many round ball. Reading a Bevel Brothers article about bottom pour pots and the round ball produced. So, I cut several of my cast round ball in half. Each one had an air pocket inside. It would create a slight unbalance in the ball. I have since switch to a ladle for pouring ball. A faster fill and no air pockets.
I will pour enough roundball each winter to last for the shooting season. .45, and .50