if rust is present in the gas system, soak in brake cleaner or a similar product that will break down the rust and any built up crud. DO not use any tools or brushes that will scratch the inner tube of the gas system. Do not oil up your gas system, it is designed to be dry, and oil would not be a good thing in there. Once cleaned, spray thoroughly with g96, wipe it all down dry...... then hit the range. The barrel should be chrome lined so there probably will be nothing required other than a usual careful cleaning with bore solvent as you normally would after a day at the range. The chamber is another thing altogether.... careful inspection is needed here and if rusting is present, follow same instruction as gas system.