Very annoying and in some cases this has happened wile fitting a scope to the rifle, my mate dropped a new scope onto his new rifle stock wile fitting it, Accidents happen and theses dents on rather lovely walnut stock can depreciate the re-sale value of your rifle. I know we can't wrap our rifles in cotton wool they are meant too be used and enjoyed.
So, all is not totally lost, here is a video, and a method to remove some small dents in wooden rifle stocks this could help.
see bellow...
https://www.youtube.com/watch?v=y4HLXGmXwdg
