I can't decide

You need not worry about rust "growing" if you don't remove the rust so there is no need to rush your decision. Just heat the metal where rust exists (or any other pits that could harbor a micro-environment) to over 200 F for a few minutes. Rust forms from oxygenating iron atoms. This doesn't occur unless H2O is in contact with the iron. Drive off the H2) then keep the pistol in a dessicated environment (easiest way to do this is create a moisture barrier between metal and H2O in air--such as with oil--the same thing in skin moisturizers that keep water from evaporating from skin). So, heat gun, put on very light oil to get into micropits and crevasses at rust spots, and grease or use heavyweight oil on gun for more long-term protection. The rust will not spread following removal of H2O.


This is one way to treat cold-blued steel after cold-blue treatment. The cold blue often is in acqueous solution and will quickly turn rusty red. Heat the steel to drive off the moisture and then protect with oil or grease--the rust won't form.