Restoring finish on a Topper Model 158?

[Beltaine]

First off does anyone know what this kind of finish is called?

 

I have an old Topper Model 158 in .410 and the receiver is covered in surface rust. I want to clean it up and possibly restore it.

 

What would be the best way to start? Is this type of finish restorable or is it going to be gone forever once I remove the rust?

[Garufa]

The finish is called color case hardening or just case hardened and if you strip it you will never get it back, at least not in your garage.  How much rust is on it?  You might be able to get a good deal of it off with 0000 steel wool and oil.

Edited January 25, 2013 by Garufa

[Beltaine]

It's pretty much solid brown but I can see the stripes in the finish underneath. I scrubbed with paper towels and some frog lube and it looks better but is still pretty brown. I'll get a pic up when I get home from work.