I've never been able to hit the broad side of a barn with .308 bullets.
Odddly enough, some factory ammo is loaded with .308's, even though the only Mosins with true .308 groove barrels are limited to a few Finns.
Most rifles will not shoot .308 well. Loss of pressure, and instability, as the bullet spins down the barrel.
Ideally, with any rifle, the diameter of the slug should match the groove diameter of the barrel.
Shoot the .311-.312 bullets. For many of us (including me) that handload, the .311, 174 grain SMK is the winnaaaa...I shoot mine (sporter) at 600 yards with that bullet over 43.5 of Varget.