I have also used recovered lead from the shooting range.
Be sure to flux and skim the wheel weight "lead" before you use it, there is a lot of impurities in the wheel weights.
If you don't know how to flux lead, once the lead is melted and flows smoothly from your dipper, add a small pinch of wax or bullet lube to the mixture.
It will smoke a bit, lighting a match will take care of the fumes from the wax, the lead will NOT catch on fire.
The impurities will be forced to the surface of the lead pot, skim them off with an old metal spoon. The lead should shimmer like untarnished silver...
There may be small black flakes still in the mix, the size of ground pepper, you are not going to get it all out, but you can reflux if needed.