You want to use a
little beeswax/alox to lube your sprue plate- heat the mouldup and touch a lube stick to the top of the mould block- you don't need much.
Before using the moulds, boil them in water, then scrub them out with soap/water and a toothbrush, make sure to let them get good and dry before using molten lead + water= explosion.
If some of the stuff gets into the cavity, it will leave wrinkles- run your pot to its max temp and just keep casting until the stuff burns/boils off. It might take 20 bullets or so, but you can toss the bullets back in the pot and reuse them again
Helpful hint- don't run your Pro Pot dry- you'll get clogs and drips from debris running through the spout.