The advantages of the 6.5CM are not tied to muzzle velocity.
- case/cartridge geometry fits better in short action magazines. - standard twist rate of 1/8 for the longer bullets. - reasonably priced match grade factory ammo suitable for long range use. - reasonably priced factory rifles that shoot well.
Combine those factors with a laser rangefinder and scope with turrets, you have a lot of things working well together.
