We muzzleloader shooters tend to be a cheap bunch so finding a source for good, clean, FREE lead is always a plus.
Every hospital of any size at all gets a considerable amount of lead in the form of small pigs (no they don't look like pigs, they look like little cups with a lid but they're called pigs). They are the shipping containers for radioactive stuff used in the nuclear medicine or radiology department. After they remove the glass vial with the whatever in them, the pigs are just tossed out. I have a doctor friend at our local hospital who simply asked the guys in the radiology dept. to toss them in a box rather than the trash. Every now and then he goes by and picks up a box, puts it in his car and tells me to come get it. Great lead, absolutely clean and in convenient size pieces to toss in the lead pot.
Tom