Quite right. The weight of the slugs alone means little. And while I wouldn't hesitate to tag my moose were there to be an unexpected opportunity with a 200 PSPCL in the 35, that isn't the bullet I'd choose for it if moose was what I was hunting specifically. And though the 200 XFB, TSX, or TTSX would all be more ideally suited in the 35 if one were collecting a large animal like a moose, it isn't a bullet one could count on to penetrate near as well as the same weight and type of bullet in the 300 Mag. The Whelen is much more of a niche rifle than is the 300 Win Mag, the latter being one of the top choices for all-around rifles one might pick for Alaska, perhaps a bit heavy in some other places in that role.
Don't get me wrong, I love the 35s, but you have to respect those cartridges that are effectively boring and often beyond realm of looney rifle hunters.
