Ok ladies and germs.
here's what I do. As a suggestion only of course.
this works for me..
I live in the city of Fort worth.
I get my lead from scrap yards, usually about a $1.00 a pound.
they are mainly sift lead from roofing vents.
I cut them up with Tin snips, and melt them, I purchased about a pea size piece of paraffin wax and it will do 1 of 2 things. Either flame up or smoke like crazy. Do NOT do this in your house. Unless you want a butt chewing from your other half, and no I'm not talking from personal experience, I'm not that crazy.

it will bring all the impurities to the top. Scoop them off . Bingo almost 100 pure lead.
a good temp is about 800° but if the lead is hot enough it will not stick to your ladle.
I cast them into 2 pound round molds, they stack better on the shelf.