Red Dot Sight

Pssst! Let us include you in on a secret: There is in fact an optimal spot to mount a red dot sight on your AR-15. A good hint is to steer clear of that fancy freefloat handguard’s rail. Stick with us and follow along below because we will cover all of the bases and keep you shooting straight!

Can I Mount a Red Dot on the Handguard?

Before we get started, it is our recommendation that you only mount your red dot optic on the rifle’s receiver.

Mounting your red dot on the gun’s receiver will make your life easier.

We do not recommend mounting it on the handguard. There are three reasons for this:

  1. Your handguard is much less stable than the receiver of your gun. The handguard is susceptible to vibrations and play, which can throw off your optic’s zero. For these reasons, we recommend you mount your red dot on top of the rifle’s receiver.
  2. AR15s can get very dirty. In relation to this, the gas system may need adjustment or cleaning. In order to clean your gas system and barrel, you will need to remove the handguard.  If your red dot is mounted to the handguard and you remove it, you will need to re-zero the optic every time you clean your rifle.
  3. Some folks may move around their uppers from rifle to rifle. If your optic is mounted on the handguard it has a greater chance of experiencing some sort of accidental adjustment. With the dot mounted on the receiver rather than the handguard, your zero should be close when placed on a new lower.

How Should I Mount My Red Dot on My AR-15?

As a general rule of thumb, you want to mount your 1x red dot optic as far forward as you can. It doesn’t matter if it is a straight tubular style red dot, a reflex open emitter, or even a holographic sight. This applies to basically everything that lacks magnification.

Red Dot Sight
Mounting your red dot as far forward as possible on the receiver will maximize your peripheral view and situational awareness.

This is done because the whole point of using a 1x red dot is to shoot with both eyes open and increase peripheral vision. The further back your optic is, the more your peripheral vision is obstructed by the optic itself. Having the optic as far forward as it can be will increase your peripheral vision or situational awareness by as much as 30%. This is a huge amount and can help reduce tunnel vision. A very popular red dot sight for AR15 rifles is the AT3 Alpha. Check it out in this video!

The Alpha red dot sight for AR15 rifles

A good guideline is to place the front of your red dot mount so it is aligned with the second picatinny section on your receiver.  This will allow for maximized peripheral vision and will give a little extra room when removing your handguard.

Mounting a Red Dot
We are mounting this AT3 Tactical RD-50 in the second picatinny slot on the receiver.

What Is the Benefit of a Cantilever Mount?

Some optics may be mounted at this location but will cant forward over the handguard. That is totally fine as you can still remove the handguard as needed without having to re-zero your optic. If you are curious about how to remove an old-school A2/M4 carbine handguard make sure to check out this free army service manual for the AR15!

This mount is an example of one that cants forward over the handguard.

Where Should the Dot Be in Your Optic?

Maybe the most important note about 1x red dot optic location is making sure your eye line matches up to the center of the optic when the rifle is shouldered. If you have the correct mount for your red dot, this should be achieved no matter how far forward your optic is mounted. If you find yourself needing to raise or lower your head to center your eyes on the optic, you may need a different riser mount.

If you are pairing your red dot sight with some backup iron sights make sure to check out our article on Absolute vs Lower 1/3 Cowitness Sights!

The AT3 Alpha Micro Red Dot comes with three different riser heights!

How Far Back Should a Red Dot Be Mounted?

We at AT3 Tactical encourage mounting most red dot optics out as far forward as possible while still being mounted to the upper receiver and not the handguard. At the end of the day, you should do what is comfortable and realistic for your situation. Everyone needs to start somewhere so some trial and error is not out of the question.

Do you like what you see mounted on these guns? Check out this article: How To Choose a Red Dot – A Buyer’s Guide to AT3 Optics.

One Last Tip

If there’s anyone that knows the AR-15 platform, it’s the US military. As a special offer for our readers, you can get the Official US Army Manual for AR-15/M4/M16 right now – for free. Click here to snag a copy.

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9 thoughts on “Where Should I Mount My Red Dot Sight on My AR-15? [2024 Update]

  1. I have a SW AR,
    Do I have to unmount the fwd sight?

    1. Hi Hiram!

      Removal of the front sight is a matter of preference in most cases. Many folks like the idea of having them co-witness and remain a backup in case the red dot optic fails in some way.

      If you are curious about the procedure of co-witnessing backup sights and a red dot, I have linked to another article to help make a decision.

    2. If it’s a flip up sight? No, I just flip the front sight up and mount the MRM leaving one or two space open between the MRM and front sight.

  2. You hang your hat where your hat hangs best for you! Not where someone else’s hat fits their head best!

    1. “At the end of the day, you should do what is comfortable and realistic for your situation. Everyone needs to start somewhere so some trial and error is not out of the question.”

  3. I just bought a cmmg 16 inch barrel, for my ar9 9mm sbr pistol. The new barrel weights 4 lbs. I don’t think recoil will be much of a problem. My question is how far can I mount my red dot from the receiver to front of the barrel?


    John Donovan

    1. Hi John!

      Although we do not recommend mounting your red dot optic on anything other than your receiver for best results, if your handguard/barrel mount is sturdy and without any play and are not worried about recoil I cannot imagine you will have any issues. If you do then you know the reason.

      Safe shooting!

  4. Great article, some of us are dominant eye challenged. I’m right handed and left eye dominant. Please take into consideration some of us are not in our late teens or early 20s. What do us older folks do?

  5. I have a RD50 mounted on my Mini-14. It’s a great red dot.

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