I don't think that COL changes have the same impact for rifle cartridges as they have for pistol. Pistol cases are usually much smaller than rifle, and bullet diameters, for the most part, are bigger. Thus, a small change in pistol COL changes the case volume to a much greater percentage than for most rifle cartridges.
As an example, I tested the seating depth for 80 gr. SMK's in .223 to see if there was a difference in accuracy for my rifle. IMI brass, Rem 9 1/2 primers, and the same charge of
RL15. I chronoed 10 shot groups, and the results follow:
2.520 OAL, 2588 fps, ES=81, SD=25
2.500 OAL, 2581 fps, ES=91, SD=26
2.490 OAL, 2621 fps, ES=62, SD=23
Not much difference w/r to accuracy or MV with a 0.030" OAL variation. 0.006" in a .308 wouldn't change much if the load is safe to start with.