Any zinc that gets into the pot contaminates the whole batch. It makes an mess that does not flow like it should. You may be able to add powdered sulfur and skim off the dross, raise the temperature very hot and use for fishing weights or whatever, still won't cast bullets though. You must sort the wheel weights individually and make sure that no zinc gets into the pot for casting bullets for M/L or cartridge loading either. Watch the previous video in this thread.