My only casting experience is from about 30 years ago casting round balls for a muzzle loader. A little pot on a Coleman stove and a ladle was what I used back then. I have a lot to learn.
Equipment used for this lesson is a Lee bottom pour 20# pot and Lee TL 356-124-2R mold.
1. Temperature matters. I know not all Lee pots will act like mine, but it seems I have to set it on 7 to melt the lead, but if I turn it back to 5 while casting it seems to work better.
2. Amount of lead in the pot matters. I've always been of the "if a little is good, a lot is better and too much is just right" crowd. A full pot causes too much head pressure and lead likes to go everywhere. About half full is where mine likes to run.
3. Sprue plate screws back out. I'd read about this but thought it wasn't that big of a problem. I was wrong. I drilled a hole and tapped it for a set screw and have had zero problems since. I also put just a little dab of high temperature anti seize on the plate at the screw hole. Huge difference.
4. Fill your mold with lead and leave it while adding more lead back to the pot. Adding lead after cutting the sprue and dropping the boolits caused my mold to cool enough it took a couple casts to get the mold back up to temperature.
5. 10ish pounds of lead makes a whole lot of 9mm boolits.