This debate pops up quite often.
I've hand loaded, and shot all three cartridges for many rounds, and have tons of friends that do the same. I currently use, and shoot all three. I showed a customer this comparison last weekend. This is just talking the common short actions. The 6.5 Creedmoor and the .260 Remington make the same ballistics, so I'm lumping them together. I input muzzle velocities based on the maximum performance I've been able to safely achieve out of the cartridges. And these numbers are all based on a 24" barrel. Numbers would have to be adjusted based on shorter barrels. Every caliber is loaded with a Hornady ELD-X high BC hunting bullet, to keep things on the same playing field. G-7 ballistic coefficient is input based on Hornady's published BC. jbmballistics.com is the calculator. Wind drift and energy deliver is all that I am reporting. Elevation is easily corrected for. Wind is based on a 5 mph at 3 or 9 o'clock to the shot direction, and reported in Mils. If you want to use MOA, multiply these values by 3.43. I am not, again, advocating long range game animal shooting. But these numbers probably matter for someone that hates to let a feral hog or a coyote get a pass.
143 gr. ELD-X
G-7 BC .314
MV 2800 fps
100 yards 0 wind, 2245 ft/ lbs.
200 yards .1 wind, 2013 ft/ lbs.
300 yards .2 wind, 1800 ft/ lbs.
400 yards .3 wind, 1605 ft/ lbs.
500 yards .4 wind, 1428 ft/ lbs.
600 yards .5 wind, 1266 ft/ lbs.
700 yards .6 wind, 1119 ft/ lbs.
800 yards .7 wind, 984 ft/ lbs.
900 yards .8 wind, 862 ft/ lbs.
1000 yards .9 wind, 751 ft/ lbs.
162 gr. ELD-X
G-7 BC .318
MV 2750 fps
100 yards, 0 wind, 2455 ft/ lbs.
200 yards, .1 wind, 2206 ft/ lbs.
300 yards, .2 wind, 1970 ft/ lbs.
400 yards, .3 wind, 1758 ft/ lbs.
500 yards, .4 wind, 1565 ft/ lbs.
600 yards, .5 wind, 1388 ft/ lbs.
700 yards, .6 wind, 1227 ft/ lbs.
800 yards, .7 wind, 1080 ft/ lbs.
900 yards, .8 wind, 946 ft/ lbs.
1000 yards, .9 wind, 825 ft/ lbs.
178 gr. ELD-X
G-7 BC .278
MV 2700 fps
100 yards, .1 wind, 2559 ft/ lbs.
200 yards, .2 wind, 2256 ft/ lbs.
300 yards, .3 wind, 1982 ft/ lbs.
400 yards, .4 wind, 1736 ft/ lbs.
500 yards, .5 wind, 1514 ft/ lbs.
600 yards, .6 wind, 1314 ft/ lbs.
700 yards, .7 wind, 1134 ft/ lbs.
800 yards, .9 wind, 972 ft/ lbs.
900 yards, 1.0 wind, 828 ft/ lbs.
1000 yards, 1.2 wind, 700 ft/ lbs.
What's the Cliff's notes?
The 6.5mm and the 7mm both do significantly better in the wind. Remember, those are 5 mph wind values. If it were 7-8 mph, add 50% to those holds. If it were a 10 mph wind, double those holds.
Energy delivery, well the good ole' .308 Win does a great job, and beats both the 6.5mm and the 7mm out to 300 yards. At 400, 500, 600 & 700 yards the winning order is:
6.5 mmAt 800, 900, and 1000 yards the winning order is:
Of course there are many factors to choose one over the other. If a person is not a hand loader, two of the three are most likely going to shoot match grade, small, with mass produced ammo, and those being the 6.5 Creedmoor and the .308 Winchester. But they both will probably have lower speeds than what these values were based on. Rifle chambering availability is also a factor, of course. But if a guy is going to build a custom, or semi-custom rifle AND he is a hand loader he can make the rile do what ever he wants. Shorten the barrel, lose velocity, gain maneuverability. The end user has to decide. All three of these can be chambered in an AR platform, which will also reduce velocity. I call it the gas-gun tax. Then the other option of bullet weight can be adjusted for that platform. For instance I have a 16" barrel (6" less than these test subjects) AR platform .308 Win. Because I was going to be hurting for velocity, I switched over to a 155 gr bullet, and strayed from my normal H-Varget powder. Chad recommended a change in powder to gain velocity, and it worked. I managed to eek out 2600 fps MV out of a suppressed 16" AR, safely. But in order to post every possible combination of cartridge, bullet weight, and barrel length would dictate more time than I'm willing to give it.
This is maximum performance I've obtained from bolt action 24" barrels. Just as an example of what each can do. Rule of thumb, for anyone wanting to compare numbers to shorter barrels, is 20-25 fps per inch of barrel cut off. Reduce the velocities based on the new barrel length. http://www.jbmballistics.com/cgi-bin/jbmtraj-5.1.cgi