TomC,
Try to steam it out as explained above by Builder. IMO a small scratch (refinished) is better looking than any of the scratch fillers - caveat: Unless you choose a high gloss finish which will mask the shinyness of the filled area. These filled spots really stand out on a low gloss oil finished gun.

If the scratch is too deep to leave alone after steaming and light sanding, look at the shellac filler sticks from Brownells. They come in several flavors of brown, and are pretty easy to use.