Rifling twists for the .308 Win barrel. . . . . .
1:12 twists in 24" barrels have given match winning and record setting accuracy at ranges up to 1000 yards with bullets from 172 to 190 grains. 1:11 twist barrels were "the one to use" for 168's with reduced loads up to 190's with max loads when the .308 was the only thing used in most high power competitions. And the rate bullet rpm's slows down is about 10% the rate their velocity does; they don't always spin 180,000 rpm's (3000 fps from a 1:12 twist) all the way to 1000 yards.
The 1:10 was used in the 30-06 from 150 grain to 220 grain. So why not the 1:10 for 308?
If I'm not shooting, I'm reloading.