308 here...
At ANY distance I am a MUCH better shot if I practice with the rifle.
Practice = $
308 vs 6.5 = less $
Getting used to trigger, recoil, optics, and weight balance is far more important than one caliber over another.
I can't afford 6.5 after buying this rig and scope.
As a bonus, Nikon makes a great scope with a BDC designed for 308 bullet drop. (Without breaking the bank)
Put a P-308 on mine, at 12x the BDC is pre calculated up to 800 yards using 165 grain. (I use 168 Barnes TTSX)
I haven't noticed a specific optic for 6.5 yet.