There are better products for getting rid of rust.I never needed it on guns, but I use it regularly in industrial applications. Normally just wiping on a good coat on and let it sit 24 hours.I have soaked tools in it but really didn't need to soak. It will take paint, bluing off as well as other things. Reacts violently with zinc. The worst thing I've used it on is a lithium salt filter press that was 30 years old. Brushed it on , next morning it rust was gone. Metal was clean.One is Krud Cutter rust inhibitor /converter