I just picked up an M&P T AR-15. It has the flip up sites and I would like to put a quality red dot on it and want the dot to line up with the iron sites. How do I go about getting a site/mount that is regulated in this fashion?
there is no perfect "match" to line up irons with any optics. there's the matter of height deviation between the reticle and the iron sights. there is no industry standard in reticle height due to every shooter having different sight pictures and alignment based on body composition, cheek to stock weld / placement, and eyesight. essentially the same reason that iron sights are made adjustable, to adjust the shooters line of sight to the line of bore. another factor is that a quality red dot sight is built to be a reflex sight. the floating red dot does not require that you maintain a consistent sight picture to actively hit your targets. the red dot reticle will appear to float and move as you move your head adjusting your sight alignment all while staying on target. that makes an alignment with iron sights next to impossible. a very different world from a typical powered scope.
your best bet is to just ensure that whatever reflex sight that you settle on, it will co witness with your iron sights leaving a clear un-obscured sight picture with either. bothe the aimpoint and eotech line are great quality co witness, combat proven reflex sights that were designed around the ar15 / m16 platform.
just one word of caution with the aimpoint and eotech, i would only buy new from an authorized dealer. there is a rash of Chinese clones that have flooded the market that are %100 visibly correct and even include serial numbers. they only way to really tell is when it breaks, you send it back to the factory, and they break the news to you.
