Shooting trap is a lot different than shooting off a rest. Has he ever patterened his shotgun off a rest? The 30-06 is about all the average shooter can tolerate as far as recoil goes (at least that is what I've read). A 300 WM has substantially more because it uses about 20% more powder for a 180 gr bullet (referencing IMR load data and IMR4350 powder). The 300WM is not a 'plinker' and you will not shoot alot of rounds in a session. I would advise that your friend try one first.