What about the abrasives used for the polishing process. What ever you use walnuts/corn cobs to get the brass shiny again a abrasive has to be used.
What about it? Being as I use Liquid Auto Polish that OK to use on my Corvette I'm sure not worring and wringing my hands over using it to clean my brass cases. Priming compounds and powder ash would be more of a problem and I don't worry about those.