As we know, LR ammo tech never stops and the biggest change in tech has been in the 30cals... specifically wrt to FTR competition out to 1000yds.
For this comparison, consider a mag fed 6.5 CM with a 140/142gr class bullet at the typical 2700'ish fps vs a single feed FTR type 308 pushing heavy high BC bullets at elevated velocities. The wind drift at 1000yds is actually much closer today then it was even 4 yrs ago.
I compete beside Open rifles which are mostly 7mm but a few 6.5's show up. Accuracy is near identical and drift is not that far apart anymore. I have shot beside a 6.5X47L pushing 140's to over 2700fps out to 1000yds. Our initial wind setting on the scope were IDENTICAL.
yes, the FTR stuff is very specific and hot rodded.. this is not your Fed GM 168gr loads
But if you really want to shoot the 308 AND don't need to feed from a mag, build it like a FTR and be blown away by how well it can shoot at LR.
In competition, there are plenty of relays where a 308 shooter will out score the field of open shooters typically using 7mm's of some flavor.
For a frame of reference, at 1000yds the X ring is 5" and the 10 ring is 10". If confirmed, the new FTR NRA 1000yds record is 200-16X out of a possible 200-20X. I think the Open record is 200-17X or thereabouts.
The difference in match scores between FTR and Open is closing... the closest it has been in the last 5yrs.
SO, if you want to compare apples and oranges, you might be able to change this debate in favor of the "308".... at least the super sized versions used in competition.
The one thing that will not change, the 6.5 CM recoils less vs the 308. I am really enjoying shooting the 6.5 CM with the 140 class bullets.
yep, I have both so am basing this on first hand experience.
Jerry