For the sport shooter, the inherent differences in accuracy between the two are minimal. The .243 is easier to shoot well due to lighter recoil. The .308 has an outstanding record for long range accuracy (600-1000 yards) in competition. If I wanted to target or varmint shoot at ranges under 500 yards, I'd use my .243. If I wanted to shoot targets at 600+ yards, the .308 hands down.
If you are not a hunter, then choose the .243. If you want the highest accuracy, choose a target/varmint type rifle, or have one built. The rifle has far more to do with the potential accuracy than these two catridges do. Even the best shooter in the world can't make a poorly-bedded rifle with a mediocre barrel shoot well. :roll:
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