I carry my little KelTec P11 in the waist band of my shorts or in a pocket and for a while, I had a problem with the slide rusting and leaving big brown spots on my side. One day after cleaning it, I remembered a treatment I'd used on knives I made and I decided to give it a shot. Now, after cleaning my weapons, I coat all the parts that are prone to rust with a light wax. It's great for durability and keeping out moisture. I think almost any wax will do, but I like Renaissance Wax since it dries hard relatively quickly and doesn't change the look of the gun at all.