Ramses II,
Remember that extreme range accuracy and performance is not all about velocity. Consistancy is much more important then an extra 200 fps in muzzle velocity at long or extreme range.
The 6.5mm284 is far easier to get to shoot extremely consistant from shot to shot and this is why it is so popular, also the fact that it has very low recoil and is relatively easy on a barrel and brass is very easy to get.
Extra velocity is a bonus as long as the consistancy stays the same, the larger the case capacity under a specific bore diameter, the more difficult it is to get that extreme quality consistant load. It can be done though, just not as easily as the smaller rounds.
Course you combine consistancy with higher velocity and you get a more more impressive numbers down range for sure.
Good Shooting!!
Kirby Allen(50)