Zak, one of the easiest and accurate methods to check center shot is to do the following. Shoot one arrow at 15, 20, 25, 30 and 35 yards using your 20 yard pin on the same aiming point. Your arrow should be in a straight line down the bales. If your pattern moves off to one side or the other you need to adjust your rest in small increments in the same direction you arrow tail off.