Are you wondering: ‘How to mount the scope on ar 15 with front sight?’

The Ar15 is a very popular and high-quality rifle, but you may struggle with using its fixed front sight scope. Upgrading the regular stock scope on the front sight of the Ar 15 can increase your shooting skill significantly.

Based on the step-by-step guide provided in this post, you can learn to mount the scope on the Ar15 effortlessly. Continue reading, and I will show you!

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How To Mount Scope On Ar 15 With Front Sight? 

You can install the scope on the Ar 15 with front sight, as the component does not hinder the physical installation. Yet, the process is quite complicated.

You will be able to see the sight via the scope with low magnification. However, you cannot see the view on scopes with higher magnifications. Follow these steps carefully, and you can mount the scope on Ar15 with minimal effort.

The process is much simpler if your rifle has a front sight that can be flipped up.

Without co-witnessing with the iron sights, you just need to flip down the front sight and mount the scope.

The process is more complicated for the fixed front sights (FPS). This type of front sight may hinder the scope’s view with lower magnifications.

Without co-witnessing the red dot with the iron sights, you will encounter some difficulty and distractions when aiming and shooting.

How To Mount Scope On Ar 15 With Front Sight

Gather The Needed Material 

Here are the required tools to install the scope on Ar 15 rifle with a front sight.

  • A torch wrench
  • A hex bit tool
  • Rubbing alcohol
  • Cleaning patches
  • A separated mount (optional)
  • Gun vise (optional)
  • A bubble level

You need the torch wrench to install the firearm easier, while the rubbing alcohol helps you clean the gun and the screws. For the scopes that don’t have an integrated mount, you can buy a separate mount.

You can hold the gun by hand, but a gun vise will help you save a lot of effort. Finally, the bubble level enables you to level the scope properly without ruining its accuracy.

Absolute Or ⅓ Co-Witness

Absolute means that the front irons, the rear, and the red dot are perfectly aligned when you flip up the irons. Another option is ⅓ co-witness, which means that the rear and front are aligned with the lower ⅓ view of the red dot.

Your Ar 15 rifle has a red dot that is designed to work with both ⅓ and absolute co-witness. The absolute co-witness is the best choice when you have flipped-up irons. If you don’t have the flipped-up iron, go for the ⅓ co-witness.

Unload The AR-15 Rifle

It is very dangerous to handle a loaded weapon. The first and most important thing is to unload your Ar-15 rifle.

It ensures your safety when you accidentally press the trigger. Remove the magazine first and check if there are any bullets left in the chamber.

You can apply the alcohol to the cleaning patches and clean the dirt or excess oil in the rifle’s components. Before mounting the scope, you need to remove the front and rear sights of the gun.

Removing the rear sight is very simple, but be careful with the potential gas block inside the front sight. Remove the screw and get it out of the flat upper receiver to remove the rear sight.

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Place The Rifle

Set your Ar 15 rifle on the gun vise after unloading and cleaning. It will help you secure the position and install the scope easier. The tool also helps you test the precision of the scope after installation.

Use the bubble level to place your gun in a position aligned vertically with the scope. These steps increase the accuracy of the weapon.

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Attach The Scope Mount 

The steps are quite different based on the type of scope mount equipped on your scope. For the scopes with a red dot, they have a built-in optic and scope mount that can be attached to the rail quickly.

Don’t place the mount on the upper receiver, or it may cause unwanted stress on the rifle’s tube. You can use the torch wrench to adjust the screws to suitable torque levels.

Then you need to tighten and stabilize the mount at that torque level. The hex bit tool can help you avoid over-tightening the scope and external damage.

Place the Scope on the Scope Mount

The next step is to place the scope on the mount after attaching the mount to the rifle. For the red dot, you can skip this step as the scope is already attached with the mounting.

If you use a separated mounting, you can attach the scope based on the provided instructions. Each mounting works differently, but you need to place the rings on flat surfaces. Also, don’t put the scope close to the barrel.

The gap between the two rings should be equal so that you can adjust the optic with ease. The last step is to adjust the eye relief to your desired position.

Level the Scope

You can use the bubble level to level the scope when everything is set in place.

First, adjust and align the reticle using a verified target (the door jamb, for example).

Then, place the bubble level to align the crosshair on the scope. When the optic is aligned, you can aim and shoot with more accuracy.

Lap the Rings

Lapping the rings can give more precise contact between the optics and the rings, but it may damage the ring. You should find a gunsmith who has a deep understanding of the gun’s structure to do this step.

For more in-depth instructions, consider watching the video below.


The bubble level is essential for mounting the scope on the Ar-15 rifle, so you should prepare one before installing the scope. Avoid over-tightening the sight as it may cause damage to the gun.

The optics may not be accurate after installation, so you need to adjust them accordingly. It is best to mount the scope on the free-floating rail to get higher magnifications.

Higher magnifications mean that the front sight is not obstructed and hinders your view, enabling you to shoot more accurately.

The low magnifications from 2x-4x may cause front view obstruction. So, higher magnifications (9x+) are recommended to get rid of the annoying obstruction.

How To Choose The Suitable Scope For Your Ar 15?

The first thing to consider when choosing a scope is its magnification level. A 9X magnification means that the target is nine times larger when looking via the scope.

You should choose higher magnification levels (8X at least) to get a clear view and shoot with more accuracy. Also, the larger the scope’s diameter, the better.

Larger diameters allow more light to get in and give a clearer view.

Although they will make your gun heavier, you will quickly get used to the weight. Meanwhile, you should choose smaller scopes for long-range shots.

Lastly, a fully and multi-coated scope is the best option. It has many layers of coats on the surface that decrease the glare and give you clearer aiming views.

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Final Thoughts

Choose suitable scopes based on your preferred shooting range and the weight of the Ar 15 rifle. Mounting the scopes is a piece of cake if you have the required tools and follow the steps correctly.

I hope that the instructions provided in this post can help you mount the scope on Ar-15 successfully. Thank you for reading!

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