I recently bought a new rifle---had considered the 6.5 but came home with a .308----more oooommmppphhh and way cheaper ammo.
Way cheaper?
6.5 CM ammo
https://www.midwayusa.com/product/4...oor-129-grain-interlock-spire-point-box-of-20
https://www.midwayusa.com/product/2...nition-65-creedmoor-143-grain-eld-x-box-of-20
308 ammo
https://www.midwayusa.com/product/2...ter-150-grain-interlock-spire-point-box-of-20
https://www.midwayusa.com/product/5...tion-308-winchester-178-grain-eld-x-box-of-20
more oooommmppphhh ?
Forget energy numbers, bullet penetration is what kills stuff. The bullet on the left is a 143 gr 6.5. Bullet #2 is a 150 gr 308. While the 308/150 leaves the muzzle 100 fps faster the 6.5/143 out penetrates it at any range, on any game. And within 200 yards the 6.5 is faster with more energy, shoots flatter, and has less wind drift and with 20% less recoil.
Bullet #3 is a 178 gr 308. Now we have equal penetration compared to 6.5 and similar energy, wind drift and trajectory numbers out to about 500 yards. But now with about 25% more recoil.
For hunting inside of 500 yards there isn't much difference other than recoil if you use the heavier 308 bullets. but with the more commonly used 150-165 gr 308 bullets the 6.5 is the better choice. Beyond 500 yards for target shooting it isn't close. The 308 starts running out of gas at about 800-900 yards. The 6.5 is still viable well past a mile.
I've used 30-06 since the 1970's. I'll never say anything bad about the round. But until you get to big bear, moose, or elk it isn't necessary. It probably was always more gun than needed, but certainly with todays modern bullets it is way more gun than 95% of hunters need. I downsided to 308 years ago to get less recoil. I have lots of 308 rifles that I like and ain't selling. But I've experimented enough with the 6.5 CM to say it is the better cartridge. At this stage of my life I'll just use what I have for the rest of my hunting career. But I'd advise any new shooter to go with the 6.5 over 308 every time.
For hunting it is probably more closely compared to the 270 which is 6.8mm and is a proven game killer. The 6.5 CM shoots the same bullet weights 100-150 fps slower than the 270. But within 200 yards have almost caught up in speed. Anything the 270 will kill, the 6.5 CM will kill and at the same ranges. And do it with less recoil.