If it's on a field gun, I would leave it alone, you'll get more dings on faster than you can repair it, so why bother.
However, if you must, shellac sticks is another option you may try. Natural light source is important when working with shellac to assure best color match, it's not hard but it take some skill to work with, touch-up with oil afterward most likely will be reqiired.
You can get it from Brownells or any fine funiture/ wood working places.