ARMA DYNAMICS recommends a 50 yard zero for your AR-15 rifle. The 50 yard zero provides for effective center-mass hits on target at the ranges where a carbine is most commonly used. A 50 yard zero allows the shooter to use a simple center-mass hold to ranges of point blank to 200-250 yards, depending on rifle and ammunition combination.
With this being said, we also realize that what works for one does not necessarily work for another. We have created to graphics below to compare the different zeros for various barrel length and ammunition combinations to better choose what works best for your needs.
The red dot is the point of aim while the black dots are point of impact for the given distances.