I have a tire store that is saving their used wheel weights for me would I have to add anything to make them a little harder for shooting round balls in my 44 caliber cap & ball revolver I do see a lot of ones that have "Fe" stamped & these will not work for the yare steel or iron & some of the others have "Zn" marked on them & I know they can't be used I will be getting a little every couple of weeks to a month