.308
I shoot R788 in .308. I used 180 grain in the southeast 30-100 meters ,on hogs, wild dogs and white tails, then I switched to 150 grain out here in western oregon 75-250 meters after I missed my one and only miss.
It was a Roosevelt Elk, he was 320 yards away and way-way down in a canyon. The elevation diference and a snow-covered fir limb at 200 meters got me. Snow and rain on the scope, toughest shot I ever made. I often wonder what would have happened if I had an Od 6 that day.
After that miss, I switched to 150 grain and I am on target again at 260-
300 meters out and 150 meters down. Muzzle to target elevation difference maters big time; and it occurs most of the time out here.
When I shoot side by side with my buddy, we are 150 meters above the targets and 300 meters away; (we aim at the same paper plate) his Od 6 in 180 grain strikes the exact same place as my .308 does. I don't know about energy or FSP. We thought is was a coincidence but ten shots each and they hit the same place.
Previous comments about picking the rifle then the caliber are correct, also consider the true limitations of the calibers and yourself. Some rifles don't handle the caliber well enough to exploit the capabilities of an Od 6..An Od 6 would put me in the ER.
There is something about a .308 though; the balance, economy and effectiveness in the 150 to 180 Grain bullets at the appropriate ranges.
Some data I got a while ago, PM and I can give you the entire word doc.
Cartridge (Wb@MV) Bullet BC 100 yds. 200 yds. MRT@yds.
.308 Win. (150 BT at 2800) .435 +2.7" +1.7" 3"@135 275
.30-06 (180 Sp at 2700) .483 +2.7" +1.5" 3"@125 269
I seen plenty of elk taken with both. The 150 Gr in .308 does the job with well placed shots (provided
you avoid snow-covered fir limbs)