Under best case scenarios rounds like the 6.5 CM will absoloutly kill elk and moose out to 400 even 600 yards. When I say best case I mean the typical hunting show/magazine broadside pose with the hunter having a perfect prone rest and time to range said perfectly calm, perfectly posing critter on a sunny, windless evening. I would say that in real world hunting conditions in most of the country and in the situations which I hunt, that happens in about 5% of the kills I make.
Of course I don’t consider an 06 or the 6.5 CM to be a great choice for a long range hunting. Given similar velocity and similar bullet construction I’ll take a heavier, larger diameter bullet on large game every time. A 140 gr 6.5 round is not going to have the inertia to penetrate heavy bone and muscle like the 180 gr .308 round will. If you are doing long range hunting I’d go skip both the 06 and the 6.5 CM. Inside of say 500 yards on deer either will work, on stuff larger than deer, either will work but the 06 will work more “ better” under real world hunting conditions.
Don’t get me wrong the 6.5 CM is an okay round. But given the choice of quality 6.5 rounds available in a short action I’d take a .260 all day every day over the CM and a 6.5 PRC all day everyday and twice on Sunday over the CM. Or I can just shoot my daughters 6.5-06 in a standard action which gives 6.5 PRC performance and accuracy. In my opinion the 6.5 CM has only taken off over the .260 Remington due to a cool name a marketing hype. It offers nothing over a .260 Rem in fact it offers less.
Now back on topic.
If I was banging volume steel or paper and occasionally shooting a deer the 6.5 CM is the way to go. If I was buying a rifle for general hunting with the west included, and occasionally banging steel and paper I’d be looking more towards the 06.