I use wheel weights all the time. I normally add 1-2% tin to the weights to improve casting and to toughen up the metal just a bit. I've cast bullets for over 40 years and have had problems in only two firearms, both semis. I shoot HP rifles both military and civi with cast as well as ALL of my handguns. I do have one HOT .44 mag load that leads the barrel a bit, but I won't change it. The load shoots to 3 inches at 100 yards out of my Contender. With groups like that, I don't mind scrubbing a little lead.