I was recently wandering around a gun page where there is a healthy amount of discussion back and forth on various topics. One of the members posted a picture of his AR-15 and the red dot was mounted on the handguard’s rail.
The member was accosted by the know-it-alls in the group, made to feel stupid (I assume), and some of the comments were brutal. This made me want to answer the following question to help some other innocent soul from the same fate at a later date —
Where is the best place to mount the red dot optic on my AR-15?
The best practice is for you to mount the red dot or similar non-magnified optic is as far forward on the upper receiver as you can (not the rail). This allows you to use your peripheral vision, shoot with both eyes open, and allow your zero to stay intact because the optic doesn’t move.
It also makes it possible to install a set of backup iron sights (or a magnifier) on your AR-15 (or pistol caliber carbine) by leaving open real estate on your picatinny rail behind the optic itself.
Let’s dissect this further.
Your rifle’s zero:
This one is very important because if you mount it in the wrong spot it could lose its zero. The reason why, is because while the handguard (AKA rail) on your rifle may be pretty stable, it still moves ever so slightly.
And if you ever need to remove your handguard for any reason you’ll throw your zero off. The forward most part of the upper receiver, where the flat top Picatinny rail is located, is the best possible place to install the red dot or an optic of any type because it doesn’t move.
Because it doesn’t move it eliminates any possibility of the optic losing zero, outside of the optic (because your optic could always lose zero on its own).
Peripheral vision and eyes open:
One of the reasons a firearm like the one pictured above makes a lot of sense is for defensive situations. There is almost nothing better equipped for a self-defense incident like the AR-15 that is properly setup for the role it’s in.
One of the ways it can be setup is with a properly mounted red dot that allows you to keep your peripheral vision intact. These optics aren’t magnified on their own and they don’t have an eye relief requirement (eye relief is when your eye needs to be a certain distance from the ocular lens to be used correctly).
With these red dots, 1X prism scopes, etc., there is unlimited eye relief which means that you can mount it wherever you want and it’ll work great.
Because you can mount it far forward, you won’t have the optic interrupting your vision. You can also have both eyes open while shooting, which may take some getting used to but totally worth it if you can do it.
Keeping both eyes open helps strengthen your ability to see threats from both eyes, increasing your reaction time and allowing you a greater level of defense.
Where you mount the optic on your AR-15 matters. If it’s a defensive weapon, you’ll want to be able to do certain things like keep both eyes open when shooting to retain your peripheral vision.
You’ll also want your rifle to keep its zero by preventing the optic from shifting even the smallest amount.
The best way to do all of the above is to mount the non-magnified optic to the furthest point forward you can on the upper receiver, and not on the handguard’s rail.
One of the first AR-15 upgrades is an optic or better sights. It’s always a good idea to mount them properly.