Don't shy away from the .300 wm..very few ever get to see a custom cut chamber in that cartridge, mainly factory junk cut chambers. A .002 per side neck clearance is vastly different animal than that .006-.009 per side factory rifle. Plus I can't imagine there ever being much of a brass issue compared to he other two you mentioned, which means you won't be begging for brass for 200 fps, a few clicks on the scope will deal with that and an animals chest cavity will hardly notice the difference. Gunsmiths might give you a funny look when you mention the win mag, heck they might not have a reamer-lol... But it will do amazing things compared to a factory rifle, find a great bullet and a little experimenting and you'll be happy, you barrel life should be fine also..can't beat .308 holes when hunting.