Why not take a buddy with a .308 to the range with your son and let him shoot it. It would probably be best if your son made the decision on which caliber. I would try to introduce a 25-06 to him too, and other calibers that are of common usage for the game in your area. I have a weakness for the 30-06, tho a good all-around caliber it kicks a little more and should be used with a limbsaver or other good protection when shooting on a range. If your son makes the decision it may mean more to him.