Strange that no one mentioned the scope on this problem. Everyone is talking about ammo. If you're on at 100 yds, 2" right at 200 yds, just catching the target at 250 and off it at 300 (on a 6" target). It may be possible that the scope is not mounted exactly correct and there is some slight canting of the crosshairs. This could easily throw your bullet either left or right.