6.5 CM is a legit cartridge. Easy to shoot, load and does well on game further than most hunters will (or should) pull the trigger. It hangs (energy wise) with .308 and even some .30-06 loads. Our 6.5 CM 143ELDX has 1450 ft-lbs at 500 yards, our .30-06 180g has 1550 ft-lbs at the same range. That is not enough difference to matter. The .308 is around 1350 ft-lbs at 500 (I use 350 yards as a max for the .308 on Elk).

RAPs are pretty good for the money. I have one in .243Win in a Boyd's 1AT stock.

I tend to look at cartridges in clusters and most of the 6.5 to 8mm cartridges that push 100 to 200 grain bullets at 2500 to 3000 fps MV will be okay for CO big game, granted with different parameters. My max distance for big game is almost always based on sufficient energy to make a clean kill. Not a fan of 6mms for Elk, but use them a lot for Deer down to Prairie Dogs. I like to use .30 or .33 caliber on Elk, but am fine with the 6.5s and 7mms. My 14 year old is using a 6.5CM (Bergara) for Elk and he shoots it better at 14 than I shot anything at 21. My 16 year old uses a .30-06 for Elk. All three of us are using .243Win for Deer this year.

Anecdotal, but I have seen more animals walk away, or not get collected, when shot with a 7mm Mag than any other caliber. Few would argue that the 7mm Mag is not sufficient for Elk. Some of that is just hunting. Practice with your kids makes more difference than adding 50 yards to their max range. All the people (including my Kids) I have taken hunting for the first time have to shoot 100 rounds in a variety of field positions at a variety of ranges over a few range sessions before hunting season. We then use that to lay down a Max distance, shot angles, etc based on their skills and caliber. Blake shot his first Elk at just under 350 yards and it was not a big deal at all. He was holding 8" groups as 550 yards with his hunting rifle and we set a limit at 350. But I have had some that 100 yards was their max, and they had to be sitting with the forearm on a pack. As their skills and/or size improves, they get more freedom in terms of their engagements on big game.