JMO, but the 'black rust stains' are blueing. If you're trying to remove that from what should be a bare silver finish on a sight scale, I'd either use an appropriate grade of wet or dry paper to match the original polishing or a rust/blueing remover. Of course, polish in the same direction as the original polishing marks.

Last edited by Chuck H; 06/15/08 07:13 AM.