Need to know how to mount a scope on a AR15? Have you ever mounted a scope to only have it misaligned and had to start over completely? It can be extremely annoying to mount a scope perfectly but our tutorial below aims to help you do this on the first try.
By following this guide step by step you’re going to reduce the opportunity for error and in the end you’ll have a perfectly mounted scope. It’s even quite fun once you begin getting the hang of it. After a few times using this guide you’ll be an expert and should be able to mount any scope with prior knowledge.
Items Needed to Mount Your Scope
Hex Bit Tool – The hex bit is used on a lot of different guns so it’s a useful bit to keep around. I’ve linked you to a unique tool equipped with the common bits and tools needed to work on firearms. It’s an all-in-one hand tool that has 18 of the most used tools for rifles and shotguns.
Torque Wrench – You’re going to need a torque wrench for adding your scope mount to your AR15 railing. Most attachments require a torque wrench to be installed and it’s just a tool you should have around anyways.
Bubble Level – Using a bubble level to install scopes or any firearm sight is very important. If you install your optics non-level it’s going to ruin your accuracy and just cause you headaches in the future. Always make sure your optics are completely level when installing.
Cantilever Scope Mount – This scope mount is a forward reach dual ring scope mount. If you already have a scope without rings this comes with two sets. This fits 20mm picatinny weaver rails.
Preferred Rifle Scope – You can choose whatever scope you prefer for the installation. You don’t need to pick up any scope rings if you get the Cantilever scope mount I link to above. If you choose a different scope mount or get a new scope just make sure you’ve got scope rings somewhere.
Shooting Rest – Using a shooting rest to hold your AR15 in place while is more than worth the money. Shooting rests are great for mounting scopes on your AR15 and using them to test newly installed scope accuracy. The one I’ve linked to here can be used for long rifles or handguns. They’re very useful and affordable.
You’re likely going to have most of these items around the house somewhere since they’re so common. The only item you can really consider skipping is the shooting rest but we highly recommend you pick one up. It makes a huge difference for the entire mounting process and will save you a lot of trouble.
Once you have everything together you’re ready to mount a scope, like one of these 1-6x scopes, on your AR15.
Step by Step instructions
You can follow the instructions below to mount your scope on your AR15. Please remember to take your time and be patient during this process. If you’ve never done this before it should be done slowly and accurately. There’s nothing worse than getting to the end only to find out you have to re-do the process because you rushed one step or forgot to align something.
Step 1) Preparation
The first thing you need to do is ready your rifle. Make sure your gun is empty, unloaded, and that it’s on safety. You can go ahead and set your AR15 up on the shooting rest and make sure it’s secure. Use your bubble level to make sure it’s on a level setting before starting. Lastly double check for all the tools you’re going to need for this process.
Step 2) Adding Scope Mount
Take your scope mount and place it above the upper receiver. Avoid placing the scope mount on both the upper receiver and the free-floating rail since this can cause unwanted stress on the rifles tube. Tighten the scope mount by hand so that it’s stable but not tight.
Now grab your torque wrench to finish tightening the scope mount. It’s important to pay close attention to your scope mount instructions at this stage. Each scope mount will have a torque level you should not go pass so make sure you’re not over tightening your mount.
Step 3) Adding The Scope
Now that your scope mount is secure it’s time to add your scope. Go ahead and now drop your scope onto the mount. The rings should sit on a flat surface of your scope.
Take the top portion of the scope rings and place them over the scope and begin securing the scope. When tightening the scope rings do so in an X pattern. You shouldn’t fully tighten the scope rings just yet. Use the X pattern to make sure there’s the same level gap on each side of the ring while tightening.
Once you’ve tightened the scope rings and a small gap remains you should be able to still move the scope around. This is an ideal time to check your scopes eye relief and find a position that suits you.
Step 4) Leveling Everything
First, take your bubble level and place it on a flat part of the tube. If you’re using a shooting rest this will be very easy. Just make sure your AR15 is completely level.
Now it’s time to level your scope. Before leveling the scope it’s very important to make sure your reticle is aligned horizontally and vertically. You can do this by aligning the reticle to a door frame or target that has been vertically verified by a level.
Once the reticle is properly aligned you can place the bubble level on the top of the scope and make sure it is aligned as well.
Step 5) Finishing It Up
You can now finish tightening your scope rings. Remember not to tighten one side first and then the other. Instead, use the same X pattern to tighten each side evenly so there’s an even gap on each side as you tighten the scope rings down.
Now that you know how to mount a scope on an AR15 and your scope is secure you’re ready to bore sight your rifle.
Commonly Asked Questions
What’s the proper scope position for an AR15? – You’ve likely noticed that every time you see a scoped AR15 that it’s in a different spot. Sometimes they’re further back and sometimes more forward. This is because there is no set location for the scope.
Where you’ll place your scope comes down to eye relief. Eye relief is the distance you must hold your shooting eye from the back of the scope in order to see the entire image produced by the scope. Generally, the more magnification a scope has, the shorter its eye relief.
Are quick release scope mounts worth it? – This really boils down to what you’re hunting and should really be considered situational. Here’s one example that a hunter ran into and wished he had a quick release mount. These hunters targets are usually around 200 yards out but on one of his trips the game he was hunting waked in the open through some nearby brush and was much closer.
The higher magnification scope made it too difficult to aim and shoot the closer game since he was unable to make out what he was aiming at. If he would have had a quick release scope and would have been able to swap to a holographic sight then he may have been able to shoot the closer game.
Can the AR15 be used for hunting? – Yes, the AR15 can be used for hunting. However, the standard .223 caliber ammunition doesn’t offer tons of stopping power. With that in mind, it’s best used for small game hunting or removing local predators such as coyote.
Related Read: Best Scope for the AR10.
We hope you enjoyed this tutorial and have used it successfully to mount a scope on your AR15. It’s very important to keep everything level while mounting your scope so don’t be afraid to over check with a bubble level throughout the entire process. It’s better to be safe than sorry and you don’t want to have to start over from scratch.