Chris, I use the WD to prevent rust on the cables of my sewer rodding machines, and hammers, saws and such, but I would not use it on firearms. It is a mixture of oil and the more volatile stuff evaporates over time and it dries to a shellack like substance that I don't want gumming up the insides of my firearms. I usually have the stuff in spray form and it tends to get everywhere in use. If you have something you've sprayed up with it a few times and let dry you can see the coating it leaves. While good for rust, it would concern me a bit around small precision moving parts. If its a firearm I need to rely on, I get a purpose made lubricant that will not shellack or harden.