I have had some success with using a polishing wheel on a Dremel with some Flitz to brighten up the chipped area. If you polish the steel well enough it will get bright and smooth enough that it is almost indistinguishable from the Nickel. You do have to be careful do not burn or chip the guns finish any more than it is now. I just did this on my inherited M36 (1951) Chief's Special with excellent results. The Nickeled screws were quite bunged up, and chipped. After trying hopelessly to buy new Nickel screws for months, I gave up! I used a small peening hammer to reshape and repair the screw heads, a set of jewelers files and Arkansas stones to re-cut the slot and make them round again. After I was satisfied with that, I highly polished them with Flitz and a Dremel and they look just like the Nickel finish. Just go slow and have a lot of patience, and you be OK.

Regards,
Chief38