Leave it, but reseal the wood with stock finish such as the Birchwood Casey stock oil finish.
Sand it and then refinish, but that will leave an indentation.
Or cut out the area, square flat with vertical sides and inlet a piece of walnut into it. Glue in place with a good water proof glue such as Gorilla Glue. Let cure.
Then carve, sand, stain seal, oil finish.
Or lastly, leave as your badge of dishonor, a reminder to do one thing at a time, especially with firearms!