i go to a local roofing place and buy the lead there, any impuraties you dont want then just dont flux the lead, its not nessary for balls only casting bullets as the flux only helps mix, ive got a lee production pot iv and im realy impressed, ive made a cupple of thou balls in .454 and36 (cant remember exact) the main thing is to keep your lead at a good temp, make sure your moulds are warm, youll notice when there too cold as they will ripple the lead, and if too hot you'll get a blue marble effect i call it, if you get this leave the mould cool down for a short while, hope this helps
no probs, ive lernt from a weeks worth of casting to many haha, fair play the chairman of my club gave me some gret advice, easy when you get into it, and saves a bucket load of cash