Having multiple pots for different alloys must be nice
For those of us that experiment with various alloys with one large pot it is perfectly fine to use the same one.
I found that the metal the pot as well as ladles are made of can be cleaned easily by few gentle impacts with a soft mallet while hot.
After I've cast lyman no 2 for example and I want to switch to pure lead I dump all the pot's contents into a muffin tray (The last bit by overturning the pot). Then I take the pot outside while it's hot and I give it few delicate whacks with a wooden handle I use to clean ladles in the same way. Then I melt all my pure lead and without fluxing I skim any dross off the surface. This way I maintain my pure lead as "pure enough". I don't flux pure lead anyway BTW.
With pure lead I always cast at 450c(840f). I use Lyman's ladle and I hold it for few seconds on the sprue hole "pressurising" the mold. I found I'm getting the best fill quality and consistency with this technique. I tried casting "as hot as the pot goes ", but all I achieved trying that was thin wires on my bullet sides where the mold is vented. I never successfully managed to bottom pour bullets(or balls) larger than 350 grains.
I also never whack the sprue cutter with anything. Opening it by hand in a welding glove is much better. Another thing important for mold longevity is to not slam it closed after bullets drop. I managed to mess one of my lyman iron molds by doing that. Since then I always close the mold gently. It is also a good idea to, every few minutes, raise the mold after closing to light and see if there is no light showing between halves. Proper mold will shut with a really nice fit. Even a tiny bit of light suggests there is something wrong. A small burr next to locator pin, a spec of lead in an air vent passage etc. I keep a soft brass wire brush to clean any specks of lead that stick to the (iron) mold. I wouldn't use a brass brush on aluminium. If I have to wipe a hot aluminium mold I use a piece of dry cotton fabric.
I have aluminium, iron and brass molds. Out of all of them I'm getting high quality bullets, but aluminium is the easiest and the fastest for me.
Here are some pictures of bullets I cast a while ago. These are all pure lead(perhaps a tiny amount of tin contamination under 0.1%) and they measure around 6bhn with my Lee hardness tester. They loose this mirror shine in storage and they look like typical pure lead bullet after few weeks.
