I've used tire weights for making my decoy anchors and that lead sucks. way to many impurities. They made very brittle anchors and I needed soft weights. But if they will work for you, I melt my lead on a coleman stove in a soup pan, been doing it for years on the same stove. The older ones had heavier grates that will support the pot even when red hot. Once the weights melt all the impurities will float to the top and can be skimmed off no problem. If you need a softer finished product the best lead I've found has been the sheet lead thats used on flat roofs, also the lead out of x-ray machines is great stuff. be careful that there isnt any moisture in or on the lead, if you put it in the pot after some lead is already melted there's going to be fireworks