I've learned you have to get a feel for each mold. I've molded a few thousand 900 gn
.62 cal bullets and you have to run way hotter than my 440 gn .58 bullets. The same go's for my 2 or 4 cavity molds. The more lead they use the hotter and faster I need to go. The more you touch the lead the more heat loss you get. I've also found the larger the lead pot the more stable the temp. I use a home made 35 lb pot for the bigger stuff and my 20 lb pot for the smaller stuff. I also tried molding straight from a big spoon over a camp fire(just to see if I could). It's slow but can be done. Never used a brass mold though.