Hi, a walnut stock is the easiest to refinish imo. Remove all the existing and sand down to at least 400 grit ( thats as far as I go). Then get a good gun stock oil such as CCL and rub in. It'll soak in easy at first and slow down over time. Don't slosh too much on at once and remove any excess before it dries. Little and often is the best way. You won't need to overseal with wax or varnish, the oil finish will build up over time. Don't put hardly any oil in the checkering, just enough to colour the wood.