Bart Bobbitt got a 3.25" 20 shot group at 800 yards with a .308.
I own more than a dozen 308s, and I have never got a 1" 5 shot group at 100 yards with a .308. I think I am doing something wrong with recoil, because I can easily get below 0.5" with bull barrelled 6mmBR or .223.
There are a lot of variables; shooter, rifle, ammo, wind, ...