We did this in the army only once, during bootcamp. The rifle, an M16 was placed on the ground in some kind of frame that kept it in place. We were then instructed to go prone and look through the sights. The rifle was pointed to a piece of paper. There, another soldier with a spoon like thing with a hole in the middle would move the spoon according to our instructions until the hole was lined up with the gun sights. Then he would mark the spot on the paper.
We repeated that process two more times. Apparently the three marks on the paper shouldn’t be too far apart else it indicated some problem with our stance or something.
What is this drill called?