Put a new stock on your 300 weatherby. You can have the thumb hole stock you want, this year. The added weight will tame the recoil to close to the same as the 7 mm mag you are thinking about. If that is not enough get a muzzle brake or super shock absorbing butt pad. With the money you save you can still afford a new scope ( maybe, depends on what stock you get). Just a thought.
