"Uniform corrosion can be slowed or stopped by using the five
basic facts;
(1) Slow down or stop the movement of electrons
(a)
Coat the surface with a non-conducting medium such as paint, lacquer or
oil
(b) Reduce the conductivity of the solution in contact with the metal an extreme
case being to
keep it dry. Wash away conductive pollutants regularly.
(c) Apply a current to the material (see cathodic protection).
(2) Slow down or stop oxygen from reaching the surface. Difficult to do completely but
coatings can help.
(3) Prevent the metal from giving up electrons by using a more corrosion resistant metal
higher in the electrochemical series. Use a sacrificial coating which gives up its
electrons more easily than the metal being protected. Apply cathodic protection. Use
inhibitors.
(4) Select a metal that forms an oxide that is protective and stops the reaction."
http://www.npl.co.uk/upload/pdf/beginners_guide_to_corrosion.pdf
Clean, lube, protect... keep dry. Basically under $10 invested in a decent firearms protectant product. For my money Rem oil it is not.
If you have had pitting, that is where the process will begin again, and again, and again... Unless, you keep it constantly covered/protected from O2 and H2O.
Dependent on humidity/H2O levels, regular wipe down of a good protectant will stop the process; at least during your lifetime, eventually it will all go to rust.