This is true. It really hit home when my son and I were at the range on Thursday to zero my irons on my new Colt AR15 A4. The eye relief to the peep and the LOP caused us to hit a little different from each other.
After having him zero it at 25 yards with a mil target, he shot 5 dead center in the bull. I shot 5 in the bull as well, both of us shooting a fresh target at 25 yards. However my 5 shot group was just a hair off from his. Not perfectly centered.
When we moved to 100 yds, my groups were about 6 inches to the left and six inches high. So, I moved the sight one click to the right and changed my hold from a combat hold/point of aim to a six o’clock hold and wound up with all five shots in a circle with two in th bull in the center and the other three touching the outside edges of the bull on the line.