I'm an M-Pro 7 convert also. Their gun cleaner is one of the few things I've found that will get the carbon rings off of the cylinder face. Follow up the cleaner with a wipe down with their CLP and you're in good shape. I have been using it on blue without any issues. One thing you want to stay away from on your blue guns for sure is the lead wipe away cloths. They will take the blue off faster than sand paper.