Here's my anecdotal relevant (first-hand) story:
We live at 8,000' in the heart of the Colorado Rockies. I have killed 20+ elk. Never lost one, but missed a couple. My 13yo son has been hunting since he was 6yo. He started on Missouri whitetail of which he has shot ~15+. Last year, he turned 12yo and began big game hunting in CO. He was using a 30-06 with 168gr Hornady Precision Hunter ammo. He took 1 elk, 1 mule deer, and 2 pronghorn (all prone with bipod). Most took multiple shots due to poorly placed shots. All were recovered. He also clean missed a gorgeous blonde bear at 200yds (standing with tripod). He shot well at the range, but as best I can surmise, suffered from "buck fever" and developed a flinch from the 06.
This past summer, he worked his butt off mowing lawns and caddying and bought himself a Bergara B-14 Ridge in 6.5CM (shooting Hornady Precision Hunter 143gr ammo). I put a Burris Eliminator III on it for him. Its a tack driver. We dialed it in and he practiced with it. His confidence was high going into the season.
Starting with pronghorn in Wyoming, we took 5 speedgoats including his buck (all prone w/ bipod). Ranges from 200-470yds. First rifle season in Colorado, he scouted pre-season, and located his bull prior to opening day. He found his bull mid-morning and took it standing with a tripod at ~150yds while it was walking slowly (only shot he had, we stopped him, but he was behind a bush). He hit back. The bull went ~200yds without an exit wound, but we tracked him and found him mortally wounded where we slit his throat.
Second rifle season, he took a doe mule deer at ~250yds (sitting w/ tripod). She walked 15yds like she was fine. Thinking he missed, he shot her again, where she went another 5yds and fell over dead. We found two well placed entry wounds ~2.5" apart. The first round was fatal.
Third rifle season, I borrowed his rifle on the first weekend. I took a calf elk at 83yds. Headshot. Dead before she hit the ground. 2nd weekend of third season, he caught up with a buck we had been chasing all week. Shot him sitting with a bipod across a canyon at 290yds. He took one step and tumbled downhill 40yds.
By the 4th rifle season, I think his confidence was so high that he knew what shots would make, what shots he wouldn't take, and was watching his hits through the scope. I would say he was in the zone. He was drawn for a special cow hunt on a piece of county owned land. We got on some elk, and were busted. I was able to stop them with a cow call, and he took a cow at 235yds standing with a tripod with a perfect lobotomy shot.
All together, we took 10 western state big game animals (11 including my ML buck) with his new 6.5CM.
I don't know the particulars of the third-hand story regarding the lost elk, so I won't speculate.
I do know that we were very successful with a 6.5CM, and will continue to hunt with it. We will stack the odds in our favor. We will get as close as we feel we can, we will only take high percentage shots that we feel comfortable taking, we will always use a rest and take prone shots whenever possible, we will track all animals to the best of our abilities and as far as necessary. That's our responsibility as ethical hunters.
