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How To Mount A Scope

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Leupold Mark 4By Trampas Swanson

As a gunsmith, one of the basic tasks I perform regularly in my shop for clients is scope mounting. This includes everything from red dot sights to high power, long range scopes. While it’s not hard to do, scope mounting does take careful measures to secure a scope level and not damage anything in the process. Just a degree off from being level could obscure your range data and may cost you that shot of a life time when hunting. Over tightened rings could crush your scope tube internals or cause a general lack of performance, while leaving screws too loose could cause the scope to fall off during recoil in the middle of your favorite rifle drill or during the heat of a gun fight.

Getting Off on the Right Foot

Let’s look a few very important factors to mounting a scope. First off, do you have a good quality scope that matches your intended purpose? Cheaply made scopes can dent or bind during mounting and become damaged during heavy recoil if not rated for the caliber you are mounting it on. Damaging an expensive scope can end your shooting journey before it even as the opportunity to get started.

Secondly, do you have good quality rings that match the diameter of your scope tube? Scopes commonly come in two sizes, 1 inch and 30 mm. Most entry level scopes are offered primarily in 1 inch diameter tubes to keep cost down and offer a basic amount of light emission. More seasoned shooter’s, often prefer the 30 mm tube for its greater light gathering ability and performance offering a crisper, brighter target image. Higher end scopes have even started offering a 34 mm scope on the market for tactical and precision shooters who demand the top 1% of what the scope market has to offer. Regardless of your choice, you must, as the end user, make sure your rings are the proper size to ensure the correct fit. In this choice, keep in mind, while aluminum scope rings are cheaper, they do tend to stretch over time on high recoiling caliber rifles and cause scope slippage and loss of zero. If bigger calibers are on the agenda, please consider a good solid steel scope ring such as Leupold Mark 4 or Vortex rings.

If your rifle requires a scope base for the rings to attach, be sure it matches to the model number of your rifle as certain rifles such as the Ruger MK77 series can be model specific to which rings can be mounted to its built in base. Not mentioned yet is the important task of making sure your scope rings combined with your scope base are tall enough to allow for the bell or large end of the scope to clear the barrel once mounted. Optimally, you want your scope to be mounted as low as possible to reduce your height over bore offset but this is only a benefit if you don’t go too low! Too many times, I have had scoped rifles brought into my shop with the complaint of the shot groupings are everywhere on the target and the scope just can’t seem to hold zero. A common factor in some of these complaints was improper clearance of the scope’s bell causing the natural “whip” of the barrel’s recoil to both jar the scope’s reticle around as well as hurt the natural harmonics of the barrel.

As far as tools needed, I’ll start by strongly suggesting the correct screw driver bits or Allen wrench size to match all screws involved; failure to do so can end up with a stripped screw that is seemly impossible to remove. Often, I will use a torque driver such as the Fat Torque Driver by Wheeler. Sold normally as a set, it includes driver bits matching the most common screws and fasteners in the firearm industry. It’s a gunsmith’s best friend on jobs like this. The largest of the Wheeler sets is a scope mounting kit that includes a handy set of scope bubble levels and a scope lapping kit (optional). Last but certainly not least, you will need a sturdy rifle rest to hold the rifle steady as you work on it. I personally use an assortment of rests depending on the size and shape of the rifle. My main “go to rest” is marketed as the “7” rest from a company by the name of Caldwell. Most serious rifle shooters are very familiar with this company and the affordable products they produce. With the “7” rest, it offers a solid platform in which to work and quickly folds out of the way for easy storage when not in use.

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Getting Started

Once you have gathered all of the proper tools and equipment, the first thing at hand to do is to make sure the rifle is safely unloaded and secured the rifle in the rest. If your rifle rest does not come with a way of securing snugly, you may consider using zip ties to make sure the rifle does not become dislodged or shift while mounting your scope. You will want to position the rifle rest on a bench or table where you are able gain access comfortably to the top of the rifle.

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Next, wipe all parts being installed thoroughly to remove any unwanted grease or dirt from the component surface areas. Once this has been done, use a very light coat of oil such as Hoppe’s 9 or Modern Spartan Performance oil to apply thin coverage to all contact areas in order to prevent future rust or moisture penetration between surfaces. If a base is needed for your rifle, this will be the first item to mount.

Lay the base on top of your rifle’s action and line the mounting holes in proper alignment. Once you are lined up and ready to install the screws, apply a small amount of Blue Loctite to the treads of each screw and install with a proper fitting tool until hand tightened. Once all the base screws are in, this is a good opportunity to check what the manufacturer of the scope base suggestions are for proper torque of the mounting screws. If it is not listed inside the package the scope base was originally in, you might find the info needed on the manufacturer’s website. Using this info, you can dial your Wheeler Fat Driver to the appropriate torque number and finish setting each screw. If you are mounting your scope by hand using the supplied Allen wrench, you will want to tighten each screw until it naturally stops and then tweak them by a ¼ turn past its initial stopping point.

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Next, you will want to mount your rings to the base. Having prepped the surfaces, seat the lower half of the rings at the desired position over the rifle’s action. Some scope bases require the rings to be seated and twisted into place using a supplied wrench while other manufacturer’s rings are mounted using a Picatinny rail. Once seated, loosely secure the rings to the base and then lay the scope into the bottom half. Shoulder the rifle and slowly move the scope back and forth until you have a natural eye relief and the elimination of scope shadow. Once this done, look at the middle of your scope and see if it is roughly centered between your rings, if not, you may want to move one or both rings to better support your scope. Once you have centered your scope and confident on where the rings will remain, use a small amount of Blue Loctite to the threads of your scope rings that secure to the scope base.

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In some cases, your base may have required the rings to be twisted into place for installation. This usually requires the need to make sure the rings are properly aligned using the correct diameter alignment bar. Using either a 1 inch or 30 mm bars, you will lay them into the ring lowers with pointed ends facing inward and then secure the top rings snuggly. If the points of the bars do not line up inside your rings, you will need to adjust accordingly. This is a great opportunity if you wish to smooth any burrs or imperfections inside your scope rings by a process called scope lapping. Start with using a lapping bar, similar to the alignment bars, place a small bit of 220 grit paste added to the bar. Moving the bar back and forth with a solid amount of resistance set by tightening the scope rings, you will lightly grind the inside of your rings with just a few passes to adequately prepare for scope mounting.

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Once you wipe the rings clean, you are ready to place the scope back into the lower ring halves where it was properly centered. For the next step, start by readjusting to the proper eye relief again and once complete, it’s time to begin leveling the scope. This is done by adding the top half of the scope rings and securing them just enough to hold the scope in place while allowing for still allowing for deliberate adjustment. Looking through the optic, rotate the scope until you feel the crosshairs are level with the rifle’s action.

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This can be confirmed with an addition of simple bubble levels. The Wheeler scope mounting kit comes with bubble levels in a unique fixture to place inside most actions to provide a square level to compare to the second level placed on top of the squared surface of the scope’s windage turret.

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Once you are level, apply a small amount of Blue Loctite to the screw threads and begin tightening the screws in an X pattern evenly to ensure the rings adjust evenly onto the scope. If your rings feature 3 screws on each side, start with the outside screws and finish with the middle ones. Once they are all hand tightened, you can then apply the Wheeler Fat Torque Wench for finial adjustments using the factory suggested torque amount located either in their original package or on the manufacturer’s website.

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With the scope finally mounted securely, the only thing left before it’s ready to hit the range is to bore sight the rifle. This can be done one of two ways, either with a bore sight laser or with a bore sight scope. With the laser option, you will simply plug the bore site laser into the end of the barrel snuggly and activate the laser. Move the rifle while it’s secured in the rest until you see the laser’s red dot projected on a wall or target in a safe direction approximately 25 yards away. Adjust your windage and elevation until the cross hairs are intersecting the red dot. Your second option involves inserting your bore sight scope into the end of the rifle barrel using the proper caliber dowel. Next, adjust the open end of the tool’s scope until it lines up evenly with the reticle while looking through the scope.

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You will see a small grid with a defined cross hair running through the middle. Make the proper adjustments to have the scope’s crosshairs aligned with the grid’s own crosshairs and you are done. Neither of these methods is designed to sight in your rifle perfectly, but they will help give you a very good start to do so and have you hitting paper on the first shots.

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In the end, the key to mounting a scope is taking your time while using the proper tools to ensure you do the job right the first time. Most large manufacturers are more than happy to provide the correct data and assistance for any proprietary screws or parts used. Learning to mount and maintenance your own scope can pay for itself with the very first time when you look at what you will save in gun shop’s time and cost!

Trampas Swanson

Born and raised in eastern NC, started shooting firearms at age 6, and life long hunter. Retired Deputy Sheriff serving as a supervisor and SWAT sniper unit with a background in narcotics and crime scene investigations task forces. Now living in Florida as a husband, new father, local gunsmith, firearms instructor and freelance writer for various firearms publications.

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