This old model 11 auto loader is a good example of what is needed to be done when refinishing metal parts on firearms that have seen a lot of use and abuse over the years. Add in some improper refinishing work and you have a recipe for a lot of hours into doing the job right.
This particular gun was in the owners family since the 1940s. It was refinished with a hot blue many years ago. But whoever did the job merely left the pitting that was present from rust and simply buffed the metal out on a wheel. This left a very uneven surface that still had pitting.
Below shows photos of the receiver for this gun. First the surface I had to start with. Then after just a little bit of filing it is seen how wavy the surface was from buffing. Some more work continues to flatten the surface out. Finally the completely polished receiver and the final rust blued finish.