Firstly - are your moulds CLEAN - and I do mean spotless - washed off all the oil that's on the mould when new?
Secondly, pre-heat the mould on the top of the pot to get it hot but not so hot the lead won't set when you cast into it.
Thirdly, don't run the pot at full temperature.
Grey finish to the boolit or ball usually indicates too hot lead pot. Wrinkles on the boolits or balls usually means cold mould/dirty mould/pot temperature set too low.
Good luck