Like everything, depends on your expectations. Elk killed with 6 Creedmoor (or 243) every year but bullet selection and most importantly shot placement is key. I'd personally opt for a 6.5 Creedmoor if elk was in my mind as a possibility. Not much difference in recoil but ability to run 140+ grain bullets like the Berger 140 elite hunter or Hornady 143 eldx or others.
My favorite hunting rifles for small to medium game are my 6 creedmoors with 105gr Berger Hunting VLD's.
But when asked by friends what to build/buy, between the 6 and 6.5 creeds, I always ask, "are you going to hunt elk with the rifle". If answer is "yes" my answer is 6.5 creedmoor. The 140 class bullets with the 6.5 creedmoor simply provide's more energy than a 105 6 creedmoor.
With that said, I'm fully confident in my ability to place a shot perfectly, and the effectiveness of the 105 Berger, to take a shot at a cow elk to 300 yards.
For big mule deer and antelope, a 6CM would be great at moderate ranges to 600+ with the right bullet.
My opinion, a 6CM, or any 6mm/.243 is light for elk. I am sure they will die fine with perfect shot placement at moderate ranges, which we all strive for. But it would suck to see a big bull across a 700 yard canyon and be undergunned for it.
Thank you all for your responses so far. 700 yards is a chip shot for most of the guys on this forum. Heck, I still think 400 is a long shot for this old bowhunter. From the sounds of it, I am needing to rethink this project.
Like has been said, the 6mm Creed is about like a .243 Win with comparable bullets. The 6.5 Creedmoor is about like a .260 Remington. I remember a time when a .260 Remington was considered marginal for elk. I suppose all of that changed with the premium bullets we have today.
I know I am old and set in my ways, IMO the 6.5 works up to elk. For elk I am a huge proponent of the 300 Win Mag. We all know that shot placement is the key, I just prefer the solace the bigger bullet provides me.
I've built two 6mm Creedmoors over the last year and couldn't be happier with that cartridge. I load all my ammo for exceptional accuracy so I don't depend on retail store availability. That case design has proven to be exceptionally accurate and I like it for two primary reasons beyond that:
1. When combined with long VLD bullets like the Berger 105g Hybrid and an 8 twist barrel, its hunting performance will rival a 25-06 on deer out to 500 yards.
2. These long VLD bullets fit in a short action magazine, improving rifle carry weight and accuracy to some extent. You can't seat one of these bullets properly in a .243 and still fit it in a short action magazine.
Mine are heavy barreled versions that take prairie dogs effectively out to 1000 yards and they are sweet to shoot. It wouldn't surprise me if one day they garner the world-wide respect of shooters similar to the .308. It wouldn't surprise me to see them as the NATO cartridge of the future since they combine light ammo carry weight with big impact in a cartridge accurate enough for long range sniper shooting in a short action rifle platform. Military and hunting rounds could be available in weights such as 58g/3950 fps, 68g/3850 fps and 105g/3200 fps for about any use out to 2000 yards or so with 26" barrels.
The ELD is a great bullet for hunting deer in this cartridge out to 500 yards.