If speed is your #1 goal my advise is lengthen the throat about .200" or so, that way you don't have 2/3s of the bullet hogging your powder space. If you want to shoot the heavy weights use a full size case, some would like to say that the wsm will do anything its brother will do, and it will up to about a 180grn bullet, so I call bs! You want speed and distance use a 4 groove cut rifled 11 twist 26" and stick with 165-190 grainers, that combo will give you the least drag and therefore more speed without affecting accuracy. When you build a 300wsm think like your building a 308 instead of a 30-06, its about the same principal.