Even though this is a gun Forum and not the reloading forum I'm going ot chime in. A 338WM and a 300WM are almost identical in velocity. You can put a bigger hole in whatever your shooting with a 338. If you want a bigger hole then go with the 338 other wise the 300WM has a much better bullet selection, your on the right track by sticking to the 300.

Swampcollie; How can you say you can't reload anything hooter than what you can buy? Thats the beauty of reloading, you can choose any bullet find what powder shoots the fastest and most accurate. On the contrary, you cannot buy factory ammo that is better than what you can do yourself if you know what your doing.