What problems are there with using lead-based wheel weights for patched round balls? I've heard people suggest that there might be problems, but I can't readily see what these would be. I know the size might come out a bit larger (as wheel weight material cools to a large size than pure lead), and that the balls would be harder, but I'd figure that with a patch, if you went a bit thinner on the material than with pure lead, you'd essentially end up with a workable shot. Any caveats?
Also, does anyone have any idea how things would be different using used lead bullets picked up off of a public shooting range? Obviously, we're talking averages here, since there'll be people at that range using wheel weights, pure lead, or whatever'll fit down their barrels--but if you're picking up handfuls of miscellaneous lead, most of it from commercially-bought bullets, what kind of results are you likeliest to get when you melt that stuff down and cast it? I'd imagine it'd be somewhere between pure lead and wheel weights, on average. What say ye?