If you decide to refinish the stock, instead of trying to sand dints and dings out of the stock, cover the imperfection with a heavy cloth and use an iron to steam the wood. The wood swells and the dint is lessened or gone.
There is a lot of helpful advice on youtube as many others have filmed themselves refinishing gunstocks.
How bad is the rust? Have you taken the action off the stock to get a better look inside?