Many shooters find mounting a new scope on their rifles an intimidating project. Done properly, and the scope and rifle combination will perform much better than the abilities of the average shooter. Done wrong, and the best shooter in the world won’t make the rifle and scope perform properly. Mounting a riflescope can be daunting but, with a little preparation and knowledge, is well within the capabilities of most shooters.
I have been planning a new rifle build which included a new scope, so this became a perfect time to mount the scope and write this article. I will discuss the scope and mounts I chose, the tools I use for scope mounting, and my step-by-step scope mounting process. The accompanying pictures are the actual rifle and scope that I chose for my new long-range rifle build.
A Bit About My Project
I love the AR platform. The early incarnations of the Armalite Rifle had their share of problems. Over time, those problems have been resolved and the AR platform is now one of the most popular rifle designs on the market.
I think that many people fail to realize the potential of the AR platform chambered for 5.56/.223. The conception of a medium-range, fairly accurate rifle persists among many shooters. In fact, when properly built, tuned, and used, the AR-15 platform can easily be a 1,000-yard accurate rifle.
When I started this build, my goal was to put together a 1,000-yard rifle from readily available stock parts. The actual build of this rifle will get better treatment in another article. However, to give you a bit of a tease, these are the components that I selected for this rifle.
- Bushmaster lower receiver
- Palmetto Arms upper receiver
- Palmetto Arms 24″ precision barrel
- Luth-AR adjustable fixed stock
- ERGO Free float forearm
- Standard A2 flash suppressor
- Aero Precision Boron Bolt Carrier group
- CMMG trigger kit
- UTG AR15 Ergonomic Pistol Grip
- Assorted pins and springs from various manufacturers
- UTG Keymod Bipod kit
- Xtreme Tactical Sports ½” Picatinny Riser Mount
- Wheeler Engineering 2-Piece scope rings
- Athlon 8x – 34x 56mm Scope
The parts we are concerned with for this article are the riser mount, the scope rings, the scope, and how to mount these on a rifle properly. There is no magic or secret knowledge to mounting a scope. Proper procedure and attention to detail are the key factors.
Before We Start – Making the Preparations
I have seen shooters mount a new scope on a rifle at the range working on the tailboard of a pick-up truck and shoot near-perfect groups. I suspect that this is the exception rather than the rule. Mounting a good scope on a good rifle takes a bit of preparation and specialized tools. The lack of these tools is probably the reason many shooters shy away from mounting their scopes.
There are many good manufacturers of gunsmithing tools that won’t break your budget. My experience tells me that the investment in some basic gunsmithing tools will pay off in the long run for most dedicated shooters. Here is what I have in my workbench and regularly use to mount scopes and other gunsmithing projects.
A Gun Sled or Other Support Device
A guns sled or vice and be invaluable when working on a firearm. Putting the rifle in a stable position and keeping it there is a challenge for many shooters. A sled can be taken to the range for testing or on the workbench when making repairs or adjustments.
I have several sleds and vices that give me some options depending on the type of project. I chose to use the bipod and fixed adjustable stock installation on the rifle for this scope mounting project.
A Torque Wrench – Keeping things in Balance
You can go crazy buying specialty gunsmithing tools. If you aren’t careful, you will soon have drawers of wrenches, adjustment tools, and gunsmithing screwdrivers. Several years ago, I cleaned out my workbench drawers. I gave away or sold many of the tools I had collected over the years, intending to reduce my tool collection to only what I needed.
One tool I will never be without when mounting scopes is a torque wrench. Most ring and scope manufacturers specify torque settings for the screws and bolts on their products. This is important when mounting a precision rifle scope. If the screws on the rings are not torqued correctly, the uneven pressure on the scope itself can make zeroing the riflescope next to impossible.
Scope Levels – Fining Up and Down Accurately
From time to time, I will get questions from friends about their scope and why it doesn’t seem to shoot well. The first thing I check is the alignment of the reticle with the bore of the rifle. I often find that the reticle is canted or that the riflescope doesn’t align with the rifle’s bore.
A set of scope mounting bubble levels is a key part of properly mounting a riflescope. Keeping everything level and true will help ensure that the riflescope shoots accurately. These magnetic-based scope levels are an inexpensive addition to your toolkit.
A Bore sighter – Finding Paper Before You Get to the Range
For many years, the only way to check the alignment of your scope was to go to the range and put test rounds on targets. Getting those first rounds on the target was often a frustrating experience for many shooters.
Laser bore sighters changed all that. With a good laser boresight, it is possible to check your scope mount and bring the scope close to zero in your home or shop. Bore sighting your scope and rifle before you head to the range means those first shots will, more than likely, find the paper target and get you ahead in zeroing your scope.
Mounting Your Scope – From Start to Bullseye
I will describe the steps I use to mount a scope on my AR long-range rifle build. These steps should work reasonably well for any rifle. Bolt action rifles may have slightly different needs or mounting systems, but the concepts are the same.
Get Everything Ready
Make sure you have everything you need to mount your scope before you start. The things you should have on or in your workbench include:
- The scope you have chosen
- The rings or mounting system
- The proper tools outlined above
- Blue or medium threadlock
- A clean level workbench
- Enough time to get the job done without interruptions or breaks
Many people overlook or ignore that last thing on my list. Interrupting a project like mounting a scope often results in problems. Missed steps, forgotten settings, or maladjustments are the result of interruptions and breaks. Avoid these if possible.
Work Safely – My Workbench Rules
I have three basic rules for my gunsmithing workbench. They are simple and easy to remember.
- Never have live ammunition in the same area where you are working on a gun. – I try to keep live ammunition in a separate room from my gunsmithing area. Separation prevents any accidental mating of live ammunition and a working gun. This rule goes back to the range rule that you should treat every gun as if it is loaded unless you have checked it yourself, so the next rule is a given.
- Treat every gun as if it is loaded until you check for yourself. – If I leave my workbench unattended even for a few minutes, the first thing I do when I return is check the gun’s action on which I am working to make sure it is in a safe condition. This check only takes a few seconds and is well worth your time to prevent a dangerous situation.
- Stay within specifications and tolerances – The only safe option, if something doesn’t fit, is to change the part for the correct fit or consult with the manufacturer. Manufacturers design firearms to operate safely. This goes for fire accessories as well. Never deviate from the manufacturer’s recommendations or instruction. Torque screws to the proper levels.
Straight and Level is the Key
The first step in mounting a scope to your rifle is to secure the firearm in a sled of vice. You want the bore of the gun to be level and the receiver to be perpendicular. A set of bubble levels is the easiest way to ensure that your gun is level and straight before you start.
In my case, I used my bubble levels on the Picatinny rail to make sure that the bore was level and that the rifle was straight up and down.
Adding a Riser if Needed
For my project, I knew that I would need to add additional height to the top of the Picatinny rail on my AR. The scope I chose has a 56mm objective lens. The highest mounts I could find didn’t give me enough lift for the objective lends to clear the Picatinny rail.
I chose a one-half-inch Picatinny riser from Extreme Tactical to accomplish this extra lift. These rail lifts clamp to the Picatinny rail on the AR upper and provide a Picatinny rail raised precisely one-half-inch.
I followed the manufacturer’s instructions for mounting the rail on my AR. I torqued the clamping screws to the suggested 15 lbs., but I did not apply any thread locker. It may be necessary to remove the riser to make adjustments.
Installing the Rings – Where in the World Should a Scope be Positioned?
When placing the scope rings on your rifle, the most important consideration is the scope itself and the scope’s eye relief. Eye relief is the optimum distance your eye should be from the lens at the rear of the scope.
Every scope manufacturer makes recommendations for eye relief distances. The way you position yourself on the rifle is critical to this distance. For the most part, this is a trial and error process. Place the scope rings on your rifle with the scope temporarily in place. Look through the scope in the same way you will shoot the rifle and check the eye relief.
On some bolt action rifles, the scope mounting holes are pre-drilled and tapped. Pre-drilled holes can limit the amount of adjustment in the eye relief that you can accomplish. On a rifle like an AR with a Picatinny rail, you have much more leeway to place the rings and the scope.
When you have your scope rings where you want them, torque the mounting screws to the recommended setting but don’t apply any threadlock at this time.
Aligning the Scope – Get it True to the Rifle
Before I go any further in the process, I stop here and check the level and alignment of my rifle. Working with the riser and the rings often means moving the rifle, which can affect these settings. Use your bubble levels on the rifle to check for a level bore alignment and proper vertical alignment.
When you are sure the gun is level and vertical, place the scope back onto the rings and check the eye relief one more time. When the scope is positioned properly in the rings for your eye relief, it is time to ensure that the reticle is vertical.
Ideally, the vertical line of the reticle on your scope would pass directly through the centerline of the bore of your rifle. Place your bubble level on the top turret of your scope. Place the bubble level 90 degrees to the sightline through the scope.
If your rifle is level and vertical, and the bubble level on the turret of the scope shows level, your scope reticle should be aligned with the bore of your rifle. Tighten the screws on your scope rings gently. Apply just enough pressure to keep the scope from moving.
A Word About Scope Rings and Screws
Scope rings come in a plethora of styles and designs. Some have a single screw to hold the rings together. Others have two or even three screws on the sections of the scope rings. No matter what style you select, follow the manufacturer’s instructions closely when tightening the screws on the rings.
In my build, I chose Wheeler engineering rings that have six screws on each ring. Wheeler suggests that you set your torque wrench to 15 lbs. and use an alternating pattern to tighten the screws starting with the center screw.
I followed these directions without adding the medium thread locker. I never add thread locker until the final step in case I need to adjust the mounts of add shims to change the alignment of the scope with the bore of the rifle.
Bore sighting and Alignment
With the scope mounted and the screws properly torqued, you are ready to boresight your new scope. I prefer to use a muzzle laser bore sight for this part of the project. I have enough room at my home to boresight at 25 yards. Many people don’t have this luxury. However, you can do an adequate job with as little as 25 feet of distance.
If you find that your new scope installation isn’t properly aligned, back up and redo the steps above and make sure your mounts and rings are properly installed. I have found some instances where I needed to add shims to a ring or a riser to make the whole system align properly. Follow the recommendations from the manufacturer if you need to add shims to adjust the alignment of your scope rings or other mounting accessories.
Finishing the Mount – Keeping Things in Place
When you are satisfied with the bore sighting, it is time to finish up your scope mount to ensure that things won’t come loose or change. I prefer to use a blue or medium thread lock on all the screws on my mount system.
With the rifle back on the sled or sitting securely on a bipod, carefully remove one mounting screw at a time and apply thread lock to the threads. Follow the recommendations on the thread lock container. Typically, I apply a single drop of thread locker to the threads so that when they are tightened, the thread locker spreads evenly around the screw.
Only remove one screw at a time and start at the lowest point on the mounts. Removing only one screw at a time ensures that the scope mount will not change position. When you replace the screws, be sure that you use your torque wrench at the proper setting.
Off to the Range
It’s time to head to the range for the final zeroing of your new scope. Give the thread locker time to set properly, and then pack up your range bag. The final zeroing of your new scope should be a matter of making fine adjustments to the windage and elevation of your scope. My tips and tricks for zeroing your scope are available in another article on the website.
Don’t Be Intimidated – Mounting a Scope isn’t Black Magic
There are no arcane secrets or black magic arts involved in mounting a rifle scope and getting superb accuracy. The right tools make the job much easier. Following a step-by-step process ensures that everything goes together correctly.
I hope that this article encourages you to make mounting your next scope an in-house project. It is a satisfying day when you zero a scope that you chose and mounted yourself. Please use the comments section below if you have any suggestions, tips, tricks, or thoughts about mounting rifle scope. We all benefit from sharing and helping each other. Be safe and shoot straight.