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How to Mount a Scope (And Not Screw It Up)

Correctly mounting your scope doesn't need to be scary. We cover the essential tools and walk you through the entire process for bolt guns and AR-15s.

    Scope mounting can seem like a huge undertaking.

    After all the painstaking research on calibers, shooting platforms and opticsyou want to be sure your scope and the bore of your rifle are both pointing at the same target when you head to the range.

    With a few simple tools and some patience and attention to detail, anyone can mount their scope and do it right.

    Nick Cage You Can Do It Meme

    Whether you are mounting a scope using traditional bases and rings on a bolt action rifle or you are using a cantilever one-piece mount for your AR, the basics are the same. 

    Table of Contents


    Really, it’s a lot easier than it sounds. Watch – I’ll show you!

    Basic Tools

    The tools needed are few and simple but it is critical that you have them. While “normal” tools can work, they run a real risk of damaging your optics.

    Proper Screwdriver Bits

    Some mounting systems will have slotted screws for the base and rings. Some will have Allen head screws, some will have Torx head screws and some will have large nuts that require a socket. Purchase a good set of gunsmith bits and you’ll protect your fasteners and have tools that will last a lifetime.

    at Brownells

    Prices accurate at time of writing

    Prices accurate at time of writing

    Available Coupons

    Another note, not all bits are made equal. In fact, gunsmithing bits are a good bit different than “normal” bits. Normal bits are cut in a fashion that while cheap, doesn’t allow the bit to completely seat.

    This can lead to improper torq, stripping of the screw, and damage to the firearm.

    Hollow Ground Bits

    Gunsmithing bits are hollow-ground and allow the bit to seat properly, thus giving better torq, reduced wear, and far less chance of damage to the firearm.

    Proper screwdriver bits are a must when working on firearms.
    Proper screwdriver bits are a must when working on firearms.

    Torque Wrench

    The Fat Wrench is a simple torque wrench that is quickly adjustable for your base screws, ring screws and action screws. Proper torque keeps everything tight and square and ensures you do not tweak something during the mounting process.

    Wheeler FAT Wrench
    Wheeler FAT Wrench

    Wheeler also makes a digital FAT Wrench, this comes in really handy if you’re doing a lot of optics or if you’re mounting sensitive optics such as high-end precision long-range scopes.

    at Amazon

    Prices accurate at time of writing

    Prices accurate at time of writing

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    Get the BLUE, medium stuff. This will effectively keep your screws tight, but also allow you to remove the screws later so you can change mounts or optics.

    at Amazon

    Prices accurate at time of writing

    Prices accurate at time of writing

    Available Coupons

    However, double check the owners manual for YOUR scope and rings. Some brands, such as Vortex Optics, recommends to not use Loctite since it can act as a lubricant and cause you to over torq your rings.

    Bubble Levels

    These are used to level the rifle and level the optic so your vertical and horizontal scope adjustments are perfectly in line with the bore of your rifle.

    at Amazon

    Prices accurate at time of writing

    Prices accurate at time of writing

    Available Coupons

    Rubbing Alcohol

    Use this to clean the receiver or rail, bases, rings, and screws prior to mounting. You do not want oil in or on your scope mounting system.

    Rubbing Alcohol
    Rubbing Alcohol

    Cleaning Patches

    I use some 2 ½ inch square patches to clean my parts prior to mounting.

    at Amazon

    Prices accurate at time of writing

    Prices accurate at time of writing

    Available Coupons

    Dial Caliper

    This can be used to help level the rifle with a bubble level and there is a quick way to check to see if the scope and rifle are square to each other.

    Dial Caliper
    Dial Caliper

    You can get a good old fashioned dial caliper like mine or you can get a digital version.

    at Amazon

    Prices accurate at time of writing

    Prices accurate at time of writing

    Available Coupons

    Gun Vice

    A way to keep your rifle or upper secure as you work. Trust me when I say this is by far the tool that will make your life easiest. You can get away with a starter gun vice, but if you’re a trinkerer – get a skookum vice.

    For a starter vice, I would recommend the Tipton Best Gun Vice.

    at Amazon

    Prices accurate at time of writing

    Prices accurate at time of writing

    Available Coupons

    It’s solid, built to last for the home gamer, and will allow you to work on almost any type of firearm and most bows and crossbows as well.

    However, if you’re really looking for a vice to last or if you work on your guns a lot – my favorite gun vice is the Tipton Ultra Gun Vice.

    at Cabelas

    Prices accurate at time of writing

    Prices accurate at time of writing

    Available Coupons

    Finally, you need your optic, your base, rings, and screws.

    Mounting The Scope on a Bolt Action Rifle

    For this project I’m working on a Savage Axis package gun I won at conservation organization fundraiser last year. The rifle has a round top receiver and came with Weaver style two-piece bases and rings. The scope is a simple Bushnell 3×9.

    First, lay out all your tools and parts and make sure you have everything you need handy.

    Lay it out, double check you have it all!
    Lay it out, double check you have it all!

    Be sure the rifle is unloaded and no ammunition is in the work area.

    Double check.

    I remove the bolt and magazine whenever I work on my guns. Isn’t it odd how many times we hear about guns going off when folks are cleaning them or working on them?

    There is no excuse for not taking the time to make sure your work area is safe.

    Patriot Patch Co - 4 Rules of Gun Safety

    Next, dab a little rubbing alcohol on a cleaning patch and remove all the oil from the top of the receiver. Also clean the bottom of the bases, the screws, the rings and the screw holes in the rifle and the rings.

    Removing the oil ensures that your Loctite cures properly (if you’re going to use Loctite, double-check!)

    Test fit your bases. Be sure the holes in the base match the holes in the rifle. Loosely screw on your bases. No Loctite in this step.

    Attach the lower rings to the bases. Pay special attention to the height of the rings in this step. In some cases, the rings are different heights. Follow the manufacturer instructions and get the correct ring in the correct position.

    Now, gently place your scope in the rings. How much room do you have between the rings and the turret? How much between the eyepiece and the objective bell?

    In my case, I need to turn the bases around to allow more adjustment of the scope in the rings. See why we do a dry run first?

    The bases need to be reversed. Note how the rings are right against the objective bell and the ocular bell
    The bases need to be reversed. Note how the rings are right against the objective bell and the ocular bell
    Now there is room between the rings and the objective and ocular bell.
    Now there is room between the rings and the objective and ocular bell.

    Once you are certain everything fits correctly you can start tightening things up step-by-step.

    Take all the parts off the rifle and start with your bases. Put just a drop of Loctite on the threads of each screw.

    Work with just one base at a time if two-piece. Snug up the screws using the proper driver bit. Now, take your Fat Wrench and adjust it to the specified torque for the base screws.

    Most base and ring sets will have a recommended torque for the screws. If you don’t find the info in the package jump online and do a search of the manufacturer of the mounting system. You will almost always find the info for the parts you have.

    If you have a problem finding the torque specs refer to the chart with your Fat Wrench. Use your dial calipers to measure the diameter of the screw and use the specs included with the wrench to set your torque.

    Next, fasten your bottom rings to the base. Follow the directions supplied with your rings. Again, a drop of Loctite on the threads of the attachment screws, snug up and torque to the specs provided.

    Now you are ready to set your scope in the bottom rings. Place the top rings over the scope and very lightly screw the rings down.

    Just enough to snug up the scope, but loose enough that you can turn the scope to level the reticle and move it back and forth to establish proper eye relief.

    Hot tip on eye relief – wear the glasses you plan to wear shooting when you set your relief. Even safety non-prescription glasses can alter your view.

    Leveling the Reticle

    You can use the two bubble levels for this step. Place one level on the action of the rifle. If you do not have a flat receiver or a rail you can insert the level in the action race to help level the rifle.

    I used the rail of my calipers held tightly to the bottom of the magazine well and put my level on the caliper rail.

    Using the calipers and bubble level
    Using the calipers and bubble level

    I then placed my other level on the elevation dial on the scope. Once the rifle levels up, turn the scope in the rings to level it. Tighten the rings just a touch to hold the scope level.

    Bubble level on scope
    Bubble level on the scope

    To ensure proper eye relief pick up the rifle and shoulder it as you would for an offhand shot, but close your eyes first.

    Get a good cheek weld and hold the rifle just as you would when shooting.

    Now, open your eyes. Do you have a full, clear view through the scope?

    Try closing your eyes, mounting, looking and checking several times. You should see a full view with no black edges or a clear circle smaller than the diameter of your scope.

    If you do, adjust by moving the scope back and forth until you have a full field of view. Now, check your levels again to be sure the reticle is still square to the gun.

    Once you are satisfied that your eye relief is proper and your scope is square to the rifle, Loctite the threads of the ring screws and start snugging them up and torquing them to spec.

    The next to last step is bore sighting your rifle. Bore sighting is simply ensuring that the centerline of the barrel is looking at the same place at distance as the scope.

    If everything is square and true you should be close. I generally bore sight at 50 yards. I find that 25 yards are often too close. Remember, your scope is likely about 1.5 inches higher than the bore and at 25 yards you will very likely not see the same target spot.

    Set up the rifle on a rest or sandbags and look through the bore and line it up with your chosen target. Now, look through the scope and see where your crosshair hits the target.

    By simply adjusting your elevation and windage turrets you can move the crosshair to the same spot the bore “sees”.

    Ready for the range!
    Ready for the range!

    Now let your Loctite cure overnight and head to the range!

    Mounting an Optic on an AR Platform

    Using a cantilever mount like the Burris P.E.P.R. (Proper Eye Position Ready) makes mounting easy and allows you to swap from an optic to open sights or place the optic on another flat top receiver.  

    at OpticsPlanet

    Prices accurate at time of writing

    Prices accurate at time of writing

    Available Coupons

    Your own testing will reveal if the optic comes back to zero after being removed then reattached. Always torque the base screws to the same spec each time.  Check out this tutorial on mounting the P.E.P.R.

    First, be sure the gun is unloaded and the magazine is removed.

    Remove the upper from the lower and remove the bolt carrier group and charging handle.

    Use the rubbing alcohol and some patches to clean the rail, mount, and screws removing all oil from the parts.

    Attach the mount to the rail and snug up the mounting bolts. On the P.E.P.R. you will need a ¼ inch drive, ½ inch socket for the mounting bolts.

    If you are not mounting a reflex sight or light or laser on top of the scope choose the smooth top rings to save some weight and prevent snagging on the rail sections.

    Set your scope in the bottom ring section. Place the top rings on and lightly snug up just the corner screws.

    In this case the scope was too far forward for optimal eye relief. A rail makes moving the whole assembly back a bit super easy
    In this case, the scope was too far forward for optimal eye relief. A rail makes moving the whole assembly back a bit super easy

    Once again, get your bubble levels and place one on the rifle’s rail and the other on top of the scope elevation turret. Level the scope reticle to the rifle and snug the ring screws just a touch.

    Bubble Level and AR
    Bubble Level on AR

    Reattach the upper and lower, and again shoulder the rifle with eyes closed. Open your eyes and check for proper eye relief.

    You can move the scope fore and aft in the rings or just move the entire mount on the rail until you find the correct mounting position. Be sure to use the same length of pull on the stock as you normally would shoot if you have an adjustable buttstock.

    Once you have established the proper eye relief recheck the level of the reticle to the rifle.

    Now, loosen one base screw and apply Loctite. Snug it up, loosen the other screw, apply Loctite, snug it up. Now torque to the supplied specs. In this case 65-inch/pounds.

    FAT Wrench for AR

    With this mount, you have six screws in each ring. With the four corner screws snugged to hold the scope, apply Loctite to the two remaining screws and torque them down on each ring.

    This will hold the scope securely and you can now remove, apply Loctite and torque the rest of the screws in each ring. Use an alternating pattern to tighten the ring screws.

    Remove the upper and lower halves again. Place the upper on a rest and go through the bore sighting process described above.

    Install your bolt carrier group and charging handle in the upper receiver, reattach the upper and lower and head to the range!

    Want another more lightweight option?  We love our Aero Ultralight Mounts.

    at Amazon

    Prices accurate at time of writing

    Prices accurate at time of writing

    Available Coupons

    A Note on Lapping the Scope Rings

    If you took your rifle to a gunsmith to have your scope mounted, they would likely lap your scope rings. But what is lapping?

    Basically, it’s sanding down the inside of the rings to even them out and give the best surface to surface interface between the scope and the rings as possible.

    Scope Lapping
    Lapping the rings for a scope

    So, you might be wondering, why isn’t this step included here?

    Simply – while the process isn’t hard, it is very easy to do wrong and ruin your rings. It is also completely unnecessary from a practical standpoint for normal field conditions.

    If you want to set your rifle up for precision long-range shooting, then it is an important step that shouldn’t be ignored. When I say “long-range” I define that as over 600-yards.

    For anything under that, there will be a fairly inconsequential gain to lapping the scope rings.

    But don’t worry – we’ll cover lapping of scope rings in another article soon!

    Notes For Those New to Guns and Optics

    Eye relief is the optimal distance from your eye to the rear lens on the scope. This distance allows you to see the full view the scope has to offer and places your eye and face far enough away so you do not get hit with the scope during recoil.

    Take your time getting the scope reticle and rifle as level to each other as you can. If the reticle looks “off” when you shoulder the rifle have someone place a level on the gun. Chances are you are canting the rifle. Meaning it is tilted to the side.

    Often where it feels most comfortable is not necessarily level. When shooting at long range this can make a difference as the scope elevation is dialed up. If not level your scope is not moving exactly in concert with the centerline of your bore.

    When zeroing a newly mounted scope, start at 25 yards. If you are on the target, most of the time you will be on at 100 yards. Do your fine tuning at 100 yards, then begin stepping out and ringing the steel at longer ranges!

    Still looking for the perfect scope? The Pew Pew Tactical Choosing a Rifle Scope Guide can help!

    Good luck with your newly mounted scope! What scope did you mount? What rings? Share your scope mounting tips and success down in the comments! Need to get spun up on the difference between Weaver and Picatinny Rails? Check out our Guide

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    9 Leave a Reply

    • Commenter Avatar

      As a machinist, I can't help but cringe at the sight of those cheap no-name calipers. Do yourself a favor and get you some Mitutoyo, Brown and Sharpe or Starrett.

      August 23, 2020 10:29 am
      • Commenter Avatar

        Roger that! Cheap calipers can read wrong and dial types with a dirty pinion gear will read OK at say .500" and skip .050" elsewhere on the scale, you'll only know when it goes wrong! I got rid of all the dial type calipers operators used on the New Brittian Multispindle machines yrs ago, scrap dropped right after that!

        January 14, 2021 12:27 pm
    • Commenter Avatar
      Bravo Tango

      You didn't say a thing about what "power" you set the scope to while setting for eye relief.

      I usually start out on the maximum power, then check it at lower magnification. Some scopes have such a huge variance between the eye relief at maximum power and minimum power that it's nearly impossible to set the scope so that you have a comfortable shooting position at both settings. In this situation, it is best to set eye relief with the scope set on the power that you will be using the most and then work back and forth between the other settings so that you have to adjust your shooting position as little as possible between settings.

      I generally use my scopes at nearly maximum power, and hardly ever at lowest power. However, I still make sure that I have as little variance from my normal head position as possible at the lower magnifications while having the optimum eye relief at maximum power.

      It is also important to check eye relief at different shooting positions, standing, sitting at a bench, sitting on the ground, propped, kneeling, and any other position you might find yourself in. It really sucks to get out to the range and to lay down behind your rifle, only to find out that the eye relief is so far off that you have to make adjustments before you can shoot, even though it was fine while shooting from the bench. A great scope, with an adequate "eye box" can make your life easier, but it's best to make sure that your scope is set for as many different positions as possible. I always start out at the position that I shoot from the most and then work through to the ones I find myself in the least.

      So, as you can see, it ain't as easy as this article tried to make it seem. However, it is worth the effort... and, at least for me, fun.

      March 3, 2019 1:54 am
    • Commenter Avatar
      Tirador Viejo

      Great info! The "bubblizing" the scope/rifle/mounts for levelness is the time consuming, detail stressing part of the process. I wrote to all the scope, ring, and mount manufacturers, and asked them to put perfect 12 o'clock index lines on all their products to minimize the bubbleizing required. As usual- birds chirping, crickets creaking, wind through the pines response. But if the rail is square, the rings are square to the mount/rail, and the scope is square to the rings; Little index lines would cut mounting time by 90%, and you could spend more fun time, shooting accurately!

      October 29, 2018 11:01 am
    • Commenter Avatar
      Kona Golden

      Be careful when using Rubbing Alcohol. Look for 96%. 91% is OK, but do not use anything less. Rubbing Alcohol typically has lanolin added to it. If you are looking to degrease parts, lanolin will not help you.

      September 16, 2018 8:36 am
    • Commenter Avatar

      Don't want to be too nit picky, but when you tighten the 4 or 6 screws on the rings make sure the gap on either side is approximately even. The gap on the left hand between the upper and lower halves of the ring is about the same as the gap on the right hand side. You can get equal torque and have one side pinched and a huge gap on the other side.

      P.S. I love this website, awesome info!

      September 10, 2018 2:25 pm
    • Commenter Avatar

      Wow! Thorough, to the point, great visuals and outstanding guidance. Plus recommendations of quality tools that won't brake the bank. You guys do it right! I'm looking forward to more!

      September 10, 2018 1:20 pm
    • Commenter Avatar

      thanks for the continuous stream of useful info. i will go back and remount my scope!

      September 10, 2018 5:57 am
    • Commenter Avatar

      Excellent info, I would add/adjust one aspect. When leveling the scope I prefer to use a plum bob line some distance out in front, looking through the scope on its lowest mag, clocking it to align the vertical cross hair to the plumb line, (double check to be sure your action is level first and still level after clocking the scope). In this way you are sure your cross hairs themselves are level/plumb to Earth and level to the action.

      Thank you again for another excellent article.

      September 9, 2018 7:12 pm
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