How to Mount an ACOG Scope on an AR-15

How to Mount an ACOG Scope on an AR-15?

Getting a new ACOG scope for your AR-15 is what most AR owners would want. It makes shooting more accurate. But mounting it is not as simple as you think it is. If you want to make your life simple, you can go to the shop and have them do it for you. But, experts suggest that you do the mounting as you will be the one to use it and not them. We have written this how-to mount an ACOG scope on an AR-15 guide to help you with the process.

We make the steps easy and simple to understand, so you don’t have to worry. Follow the steps below, and you will have your ACOG scope mounted fast and easily. The process does not have to be painful. Before you proceed with the steps, you need first to prepare the tools required in mounting.

What You Need?

Just like in other tasks, preparing the tools you need is the first step. You can’t complete the job without the tools. Listed below are the tools you need:

Torque Wrench

It will be impossible for you to complete the job without this tool. The primary function of the torque wrench is to mount the rifle scope to the AR-15 and make sure it is steady.

Scope Mount

The scope mount is the connection between the scope and the firearm.


The screwdriver will depend on your scope. Before purchasing, make sure you know what kind of screwdriver to buy. The most common type of screwdriver used in this job is the hex bit screwdriver.

Scope Rings

Some mounts don’t have it. You can purchase them at the gun store. Do not forget to label them.

Bubble Level

The primary function of bubble level is to make sure that your mount is level while installing.

Gun Rest

To hold the firearm in place while doing the installation, you need a gun rest. This will help you move freely around the rifle without moving it.


Do not forget your preferred optic for your AR-15.

Make sure all these tools are available before you proceed to work. It will be a waste of time if you run and look around for the device as you work on the installation.

Steps on How to Mount an ACOG scope on an AR-15?

The process of mounting does not have to be complicated. Just follow the steps below and finish it fast.

Step #1 The Preparation

Some of you are pretty excited and would want to go straight to installing the new scope for your AR15 rifle. However, this is not a good idea as there are things you need to do first. The first step you need to do and the most crucial is making sure the rifle is safe, unloaded, and empty. Several gun owners have been accidentally shot by their guns because they forgot to unload their weapons before installing the scope.

Step #2 Place the Rifle in the Gun Rest

Once you are sure the rifle is safe, position your firearm in the gun rest. Next, level your rifle using the bubble level and adjust if needed. This step will help you set up to mount the ACOG scope on your first attempt successfully.

The mount should be well secured on the table, and your rifle is firmly positioned on the mount as you do the work.

Step #3 Pair and Lable the Scope Rings

Prepare your scope rings. Start by pairing and then label them to know which to use on top and which is on the bottom. After that, it will be easier for you to find the right scope rings for your scope.

Step #4 Attach the Mount

After setting the rifle firmly on the rest, get the mount and place it on the gun. Follow the instruction guide on putting the mount on the gun. Usually, the mount comes with screws. First, screw the mount in place and make sure it will not fall off. Next, tighten the screws using a torque wrench. You mustn’t go above the torque limit stated in the instruction guide, or it could damage the mount.

Step #5 Check the Perpendicular and Parallel Levels

After tightening the mount, get your bubble level and check on the perpendicular and parallel levels. Move the screws if needed to obtain the proper level. It may take some adjustments, but it is necessary before you continue with the process. This is the part where you will add the mount rings bottom half.

Step #6 Mounting the Scope

Position the scope on the mount rings. Make sure the scope is flat on both rings before you put the top rings on. Next, use the screwdriver to tighten the screws up to 80% in an X pattern. Do not clockwise as it could affect the level.

Check if the eye relief is in the right spot. You take the gun off the mount to check the relief. Return the rifle in the gun rest if it needs some adjustments. Make sure the scope is where it should be.

Step #7 Finalize and Level

Using your bubble level, check both the perpendicular and parallel levels again. Next, make the necessary adjustments of screws to ensure the scope is level. If you are sure you have it in the proper position and level, tighten the screws. Finally, re-check the level to make sure nothing went wrong during the adjustments.

Your scope is now mounted correctly on your AR-15. Check the reticle alignment and adjust if needed.

What are ACOG mounts?

The acronym ACOG stands for Advanced Combat Optical Gunsight. It is a series of prismatic telescopic sights designed initially for M16 rifle and M4 carbine, but it is now also available for other firearms.

Can you add an RMR to an ACOG?

Yes, you can add. The RMR and ACOG combo is an exemptional aiming solution for longer distance shots and Close Quarter Battle that needs additional magnification. This dual-sighting system provides the user a unique tactical advantage. With the accurate aiming capabilities of ACOG and quick target acquisition of the RMR, the shooter can choose the proper aiming solution for the situation.


With the above steps, mounting an ACOG scope on an AR-15 is easy and safe. Just make sure you follow the steps, so you will not encounter any issues along the way. Just make sure to keep it level, and it should not get loose during the attaching part. Safety is essential, do not forget to empty the bullet before you start the process. If you want to share your thoughts, feel free to comment below.

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