2 ways that I know, and have done to get rid of the Sprue, Roll them Between 2 Steel Plates, or a Vibratory Tumbler with No Media in it (Brass Tumbler) I prefer my Tumbler, I like to ad some powdered Graphite to the Tumbler Bowl as well, This Turns the Balls a Shiny Black, and also gets them Really Slick. It only takes an Hour in my Tumbler and they are Done