For me, 1-1/2 inches or less at 100 yards with any scoped rifle. But have hunted with many deer killing buddies that couldn't put 5 in a 6 inch circle, but never missed a deer. I really don't know. I've seen good shooters with the finest rifles that could shoot the center out of a target, but couldn't kill a deer if it was taggged in one spot. Then I've seen some of the wildest hunters with the worst equiptment make the darnest shots on runnig deer at long distances that would make call them Sir.
3 inches or less at 100 yards. Shot placement means every thing. know you target.