I have been having problems with rust on the slide of my PF9. I was going to Durokoat it, but I discovered rust on the barrel tonight while doing a post shoot cleaning. This is the first I have seen since I have owned it. I know there are a lot of coatings on the market. I'm not concerned about looks, I'm concerned about protecting the slide and barrel from rust. What coating do you recommend and what are some reputable companies to do the work for me.