Figure out what is most important. You will getsome disagreement with this but you do not see the super large capacity cases in the winner circle at 1000 yard very often if ever. In strictly accuracy work there is a point of diminishing returns and a point where getting competitive guns in a large case is too difficult it seems. go to the hawks ridge and www.virgina1000yd.com
and look at the calibers used. You will find the 300 win mag, 300 AI, 300 weatherby and 300WSM and 308 Baer as the largest. The win mag likes 200-220, WSM 190-210, 300 AI likes 200-220 and 300 Weatherby seems to go 210-240s, 308 Baer seems to be 220-240. You will find another 4-6 cartridges based off the weatherby. Now you will always find a gun that likes out of that range, but not as a general rule. If you want to have competitive 1000 yard gun go with the tight neck .334-.336 Weatherby and leave the large cases alone. Less work on case making, quality cases, easy to load. Unless you are super experienced in the wildcat arena best way to go. Now you will have others disagree, but make up your own mind after you check for winning calibers.