I don't know how many times it needs to be said - but oak is a lousy choice for a gun stock. Too straight grained, to open grained, too brittle, too plain, too heavy, too hard to inlet, too hard to shape. Commercial stock makers have never offered oak. For many reasons.
Wood can be sealed quite well but all natural wood stocks can move with humidity and temperature changes. Quarter sawn blanks are the best. Laminated wood is better. Fiberglass is best.