Why I recommend 6.5 CM all the time, but do not own one
Back when I started shooting, if someone was new to this thing and wanted to get into the precision side of things, you were generally told to go get a heavy barrel 308 bolt action rifle, put it into a decent stock of some sort (McMillan if you had money or Choate if you didn't), get a Leupold scope on it and learn to handload. If you do not want to handload, Federal Gold Medal Match was the ammo to use.
That is still a pretty respectable way to go, but a lot has changed in terms of what's available. For one thing, quality of factory ammo has improved by leaps and bounds. It will cost you a little money, but with popular calibers you can get by with factory ammo.
20-30 years ago match quality factory ammo was hard to come by and 308Win was damn near every game in tow.
Nowadays, when someone comes to me and they want to get into deer hunting or precision shooting, I routinely send them in the general direction of 6.5CM.
It kicks a little less than the 308, flies a little flatter than the 308, still has very respectable barrel life (by the time you wear out a 6.5CM barrel, you'll know what you are doing, so you'll now if you want to switch) and is just as capable against deer-sized game.
As far as rifles go, as a first bolt gun, I usually steer them toward one of the several excellent Tikka T3X variants. There are other accurate factory rifles, but I am partial toward Tikkas and noone has yet come back to tell me it wasn't accurate enough. There is also enough aftermarket support if you decide to get serious about it: aftermarket barrels, stocks, etc are plentiful.
I have had a good number of 6.5CM rifles go through my hands. They have generally shot well and most were very shootable.
Yet, I do not own one. Why?
I have several good reasons.
One is quite simply that I am not new at this and I am not trying to do multiple things with the same gun. Now, if I were dead set on shooting NRL Hunter and trying to place well, I would probably lean toward 6.5CM due to power requirements there. However, for hunting I do not really need it since I happen to already have 308 Win that has more pop at hunting distances, 243Win that shoots flatter with less recoil, 280Rem that has more pop and shoots further and flatter and 300WSM that has even more pop and shoots even further and flatter. I also have a bunch of other guns in a bunch of other calibers of varying exotic-ness (new word?).
I keep on thinking about getting a nice 6.5CM because everyone should probably have one and every time I stop myself. I am all for getting new guns, but 6.5CM simply does not do anything for me that my current assortment of artillery does not.
Now, as was pointed out to me when I went sheep hunting, 308Win is not really a sheep hunter's cartridge. However, that happened to be the gun I shoot well and it worked out just fine. Still, I think it is fair to say I do not really have a true flat shooting sheep gun. That kinda made me think of 6.5CM, but a faster 6.5 would probably do the job better. The natural step up in speed is the 6.5PRC and I have been really thinking about one.
However, I really like the idea of hunting with a shorter barrel. I have been hunting with my 24" barrel 308WIn Fix and, honestly, I have no complaints.
However, I am not playing with 8.6Blackout in a 16" barrel and it is a notably handier gun. Once Q releases the Pork Chop suppressor for it, the 16" barrel with a suppressor will be about 24". I can live with that.
However, with a suppressor, my 24" 308 barrel becomes a 32" barrel. On some hunts it will work fine, but that will be a little unwieldy.
I could, of course get a 16" barrel in 6.5CM or 6.5PRC, but velocities drop somewhat precipitously in shorter barrel with overbore cartridges.
I might get 2800fps with a 140gr bullet out of 6.5PRC, but if I am trying to find a ballistically superior solution for a sheep rifle, I have to be able to do better than that.
I might still build a 6.5PRC with an 18" or 20" tube or something along those lines, just to claw back some velocity. That is the logical thing to do and if I have an opportunity to go sheep hunting again, I'll pick one up. Besides, I happened to have a fairly compact and lightweight 6.5 suppressor (Q's Jumbo Shrimp) that is less than 6" long.
However, the introduction of 277Fury by Sig gave me a new hope. It fits normal short actions and SR-25 magazines. That's a big plus for me. Since 277 Fury in its hybrid case form runs at notably higher pressures, I can get essentially the same speed as 6.5PRC out of the same barrel lengths except with a slightly heavier bullet. Sig's 150gr hunting ammo reputedly does 2820fps out of a 16" barrel. I would like to see it get out into the wild, so that we can get an independent corroboration of the velocities. However, this being the new military cartridge, there has to be a pretty decent ecosystem coming up.
General disclaimer: while I think 277 Fury is an excellent idea for a hunting cartridge, I do think it is a stupid idea for general purpose military cartridge. As is usually the case, the brilliant thinkers at the Pentagon went with it because they are fighting last decades war. I'll be happy to do a livestream on that if you are interested.
Going back to my original point: I am getting spoiled with short and handy rifles, so I am looking at something with similar handling qualities for a sheep gun. 6.5CM does not do that for me. 6.5PRC barely does. 277Fury offers new hope. If I can get performance that I want out of a normal short action, we are off to the races.
Perhaps I'll pick up Sig Cross in 277Fury next year to experiment with. Or perhaps I'll be able to get an appropriate barrel for The Fix
It is slow, but accurate and consistent.
This ammo showed some mild pressure signs, but not too significant. 
