Years ago I was advised to use a penny on edge to remove rust. It worked so-so. It is a good way of removing most of a really bad rust spot, then follow it up with steel wool and CLP. Now days I use fine steel wool and a penetrating oil or rust preventative, it works well. I like Breakfree CLP. I have used it for years with excellent results and I can get it any where gun cleaning supplies are sold, even Walmart. When using a good rust prohibitive, it not only helps remove rust it works its way into the pores of the steel to help prevent further rust. Good Shooting and Good Luck