Lacquer thinner but go easy with it. Saturate a piece of Burlap or other rough cloth and use the friction as much as the solvent to take it off. If you flooded the stock with thinner it could start to lift the oil negating the age an oxidation of the original finish.

If it is an all oil finish a slight amount of wax will rub out and mix with the oil. So you don't have to take every little bit off.

"When you disarm the people, you commence to offend them and show that you distrust them either through cowardice or lack of confidence, and both of these opinions generate hatred." Niccolo Machiavelli