If you have Iron sights on your AR, you probably don’t know how to use them.
If you know, you are among the very few lucky enough to have had someone teach them the correct technique.
The technique is simple. Here it is:
When you bring your rifle up the your shoulder/cheek, look through the rear aperture. Focus on the front sight. Align the front sight with the target. Ignore the rear sight.
As long as you keep the front sight aligned with the target, you will be accurate. you don’t need to consciously align the rear sight. In fact, if you are attempting to align the sights with each other, it will often reduce your accuracy. This makes aperture sights, such as are commonly found on AR-15s, very fast, simple, and accurate.
There is a science behind why this works. The following graphic explains it. But all you really need to know is to look through the rear sight, focus on the front sight, align the front site with the target, and squeeze the trigger. Similar to shooting with a red dot sight, you are only consciously aligning two objects, not three.