When we talk about polishing gun parts what we really mean is to SMOOTH gun parts.
Polishing to a mirror shine not only does nothing for smooth operation, it often ruins parts by altering the shape of critical surfaces, or by breaking through a hardened surface.
The real key is to know WHAT to polish. Often many parts don't need any smoothing at all either because it's non-critical or because it's already as smooth as needed.
If you're dealing with mil-surp guns, the critical working parts are almost always already "polished" by simple use and parts wearing in.
Assuming you're working on a 1911, some areas you might look at are:
The feed ramps in the frame and barrel. Note, that these are the areas most polished by people and are the areas that usually don't need it, and the areas most ruined.
The rear face of the trigger.
The sides really don't need it.
The front face of the disconnecter and the sloped area on the rear the sear spring leg rides on.
The tips of the center and left legs of the sear spring.
Unless you REALLY know what you're doing, stay away from the sear and hammer. This is another area often ruined by polishing.
Nothing else really benefits from polishing unless the gun is an off brand that's just plain rough as a cob.
