I would recommend the 30/06. I know it's boring and everybody's got one, but there's a reason it's as popular as it is. A 300 magnum will not be of any advantage whatsoever unless you are shooting at more than 350 yards. And even then, the only advantage is your hold over will be a few inches less than with the 30/06. 30/06 ammo is much cheaper, and the /06 is a lot easier on your shoulder and I guarantee it will be a lot more fun to shoot.