if you look at the trajectory of the bullet, it starts out below the line of the scope (by however high the scope is mounted over the barrel). The bullet is then going to slowly rise then come back down sort of like a small rainbow. If you zero at 10 yards, the bullet is still rising, so the bullet would be much higher at 25 and prob 50 yards and then begin to drop back down. Unless you are only going to be shooting at 10 yards all the time, you need to sight it in at a more useable distance, somewhere between 25 and 50.