Agreed on the 6.5's. I have taken many antelope and mule deer with 6.5x55, 260 and the 6.5x47, regardless of projectile, MV 2600-2800 fps out to 650 yards for me personally. Double lungs, heart. Head, neck and high shoulder shots.
But, you have to be willing to pass up a strong quartering shot on a beast like this with a belly of grass. I have passed on many a nice buck because I only had fleeting seconds to take him or never see him again. This picture is simply a pre-season example of the angle I would not attempt with that class of cartridge, perhaps others more skilled than I would.
The last two pics you may have already seen from the last 2 seasons. The one in the snow extreme raking 440 yard 20 degrees above me as he was disappearing into the timber. 338 lapua 260 LRX entering right rear between the RR ham and back rib, exit LF shoulder. Less than 1 minute of shooting light, last day of the season fell all the way down the mountain, DOA.
The desert buck, less than a minute of legal light, extreme front quartering shot between the RF and chest exit between LR ham and LR back rib. Fell into the canyon he was about to step into DOA, around 150 yards 300 WIN 190 SMK.
Bell killed a bunch large pachyderms with the old diminuative 7, but the shots were perfect. Like an archer, so it is with everything including firearms: location and reasonableness relative to the game at hand.
I will most likely use my 6.5 CM this Fall at times, but if I am after a particular horned beast I will take more horsepower. They still seem to die, I have yet to experience anything over killed yet.