This is the method uesed by the army to get there first sight picture for new recuits. At least when i went through that is what we did. The targets were made to represent the size of target picture you would get at 300 meters. This was a good starting point and it made you see what your target look like at that range ." Open sights" it was small!!!! I like it because you can get your rifle to good starting point with out wasting alot of ammo. Good luck