How to zero an Ar 15 with a red dot is a straight forward and simple concept with an Ar 15. There are 2 easy methods to zero an ar 15 with a red dot. One method is very simple if you have traditional back up iron sights. The second method with an Ar 15 is a little more complicated but works well if you a running 45 degree offset back up sights or no back up iron sights with your red dot on your Ar 15.