Good molds. They heat up fast. One thing to watch out for is to not overheat them. This will warp them. I usually do two sizes when I make balls. Do maybe 50-60 then change molds. Lee will stand behingd their products
Lee mold blacks are aluminum. Treated well they will cast more than you could ever use. watch the sprue cutter plate. They are hardened steel and can score the top of the mold blocks. Always use a piece of wood to knock the sprue cutter and not a metal hammer. If you can find an old clamp on handle for the sprue cutter tab, so you use your hand to open it, that is even better, but hard to find.
I usually drop the balls onto an inclined board that is covered with a few layers of cloth. The ball hits the rag and rolls down into a wide flat container/tray. Less bumping and deformity. I usually mold about a 100 and switch off. to another mold, and then back again. If it is a frequently used size, I may mold up enough to fill a 1 lb coffee can at one mold session.