As this type of optic is truly parallax free, the dot moves around as the shooter's head is moved. If the shooter raises his/her head, then the dot will appear at the top of the sighting window. The dot appearing on the top of the front post proves that you've got a proper cheekweld.
I'm a big (though relatively new) fan of red dot sights, and I plan to get another pone for my latest 5.56 build. I used a carry handle and A2 front sight for years, and thought it worked out just fine. The CompML3 is so much quicker and simpler that I was truly amazed.
