I flux with bees wax and have for years. Works just fine. I put that in the lead, and then hit it with a long nose lighter and let it burn. After I scrap the top with a piece of steel I shaped just for this, there will sometimes appear an almost colored oil slick (for better words to describe it). It has lots of blues and even some green as I remember. Once you start casting that disappears and it does not harm the final product.

I built small drop box. The drop box is nothing more then a 1'X1' square piece of pine with 1/2 inch sides around it. I then put wedges under the two sides, and squared the back side. So the drop box sits ata very slight angle. I lined it with an old leather boot I cut up. That leather will not burn, the ball will hit it the leather and not deform, and slowly roll down into the pack of casted projectiles. Wool is another good material to line the drop box with. Saves on the fingers and the bad language...