If he doesn't own a 30-06, I wouldn't suggest buying one if he does own a 308. At practical range, there isn't enough difference to squabble about. Remember, the 308 replaced 30-06 as a military rifle. People and elk are quite a bit different though....Ok "not a Gucci guy"
1) Why pidddle dick around with a 308 when you can use an 30-06?
2) A 308 produces hydrostatic shock?
3) Around the world a lot of Moose succumb to 6.5 bullets, just keep your shots realistic.
4) At one point the 243, 270WIN, 7MM Mag and 308 were all the darlings of the "marketing nuts".
5) The 6.5C is not based on MV and foot pounds of energy it is base on sectional density.
6) In the Fed Fusion line the 180gr 308 and 270 150gr have the same energy at 500 yards and equals the 6.5C energy at 400 yards. Both the 270 and 6.5 have better SD than the 308.
7) The 308 was fine for hunting and is slightly better than the 6.5C, but of course "non marketing hyped" types opt for the 30-06.
"Around the world a lot of Moose succumb to 6.5 bullets, just keep your shots realistic."
I agree, but my Great Grandad hunted moose with great success in the Alaskan Gold Rush with a 25-35 Winchester......it worked fine, but personally, I wouldn't consider either a good "Moose Rifle". Grandad also hunted deer with a 22LR. It was legal back then and he kept shots close. Other that poachers, today nobody considers a 22LR a deer rifle.