dropping them straight into cold water and letting them sit for 24 hours will harden them but for a muzzy you want them soft. Ive casted a bunch of pistol bullets but never a big conical... yet!
For cast bullets to precipitate harden, they must also contain tin, antimony and at least a trace of arsenic. Air cooled bullets will also harden in a similar manner, but will take longer and may not reach the same hardness. Quenched bullets generally reach peak hardness in 7 days or so while air cooled bullets may take a month.
If you want slightly tougher projectiles for the MLer, use pure lead with not more than 4% tin. 2% tin will make casting perfect bullets much easier.
