The rifle is to be fed factory ammo? Both are going to be pretty stout kickers with the boat paddle stock and I doubt 180-200gr .300 loads are going to feel much different from 200-225gr .338 loads. Ammo is going to be bit cheaper in the 300, with more available options. The .338 can be cut back to 22" without much loss in velocity, while the .300 generally can't claim the same. If you are going for the flattest trajectory with a duplex reticle, a guy can shoot fast 165-180gr premiums in the .300 and stretch things out a bit more than the .338, but if most of your shots are inside 300-350yds, it is really not a big deal. There's not really a bad choice between the two.
There was a laminated SS .338 M77 in the classifieds in the last couple weeks. I remember it being a good buy.
