Mounting a scope is a basic gunsmith project. You can pay a gunsmith to mount a rifle scope for you or you can mount it yourself. It requires only basic skills, a few inexpensive tools, and a little effort.
Mounting a scope on a modern rifle is rather easy. The most modern centerfire rifles have receivers that are drilled and tapped at the factory to attach scope bases.
And modern bolt action rifles have bolt handles that are designed to be operated beneath low mounted scopes.
Many brands and styles of scope mounting systems are readily available to fit almost any modern rifle.
Most base and ring sets include simple instructions that tell how install them - simple and incomplete instructions.
But do not be discouraged. Read my rifle scope mounting instructions to learn a more complete way to mount a scope on a rifle.
Yes, mounting a scope is easy. You can do it yourself. It just involves more time and work and requires more tools to do correctly than many shooters realize.
Mounting a telescopic sight on a rifle normally involves three steps:
Attach The Bases
In addition to the rifle, scope, bases and rings you will need the tools and materials listed on the left. A workbench with a clear surface is helpful. (Dropped screws will be easier to find if your work area is not cluttered.)
Be sure the rifle is unloaded and safe. Open the action and leave it open. Opening the action to ensures the bolt will not be marred by the base screws if they protrude through the receiver.
Place the safety switch to the "SAFE" position if the action allows with the action open. Look into the chamber to make sure a round of ammunition did not remain. Be sure the magazine is empty and remove the magazine if it is detachable.
Place the rifle in the gun cleaning cradle or sight-in vise or attach a bipod. A gun cradle, vise, or bipod will free your hands for other tasks.
Use a small gunsmith screwdriver to remove the scope base plug screws from the receiver.
List Of Scope Mounting Level Kit
* Items included in the Wheeler Engineering Scope Mounting Kit.
Do not use a regular flat-tip screwdriver on a gun (or any other expensive equipment).
Use gunsmith screwdrivers instead. Gunsmith screwdrivers have thicker, flatter tips designed to fit screw slots better than regular screwdrivers.
Their precisely ground tips are less likely to strip the screw slot or slip and scratch the gun metal finish than regular screwdrivers.
Double over 1/4-inch or so of one end of a pipe cleaner. Spray the doubled-over end with a degreaser intended for firearms such as Birchwood Casey® Cleaner - Degreaser™.
Twist the doubled over end of the pipe cleaner into one of the scope base screw holes in the rifle receiver.
When the tip is dirty, snip the end off, double over another 1/4-inch, and respray.
Clean that screw hole as many times as it takes to remove all of the crud. Thoroughly clean and degrease all of the scope base screw holes in the receiver the same way.
Clean the screw holes through the bases with a pipe cleaner wet with cleaner / degreaser.
Clean the screw head recesses in the bases with a cotton swab. Wipe the bases and rings with cleaning patch wet with gun cleaner / degreaser.
Spray the screw threads and brush them with a pipe cleaner. Wipe the scope base area of the gun receiver also.
Tips: You should clean and oil the rifle thoroughly before you mount a scope on it. The scope will be one more thing you will have to work around if you clean the rifle later. Also, have any repairs or modifications to the rifle such as replacing the barrel, rebedding the stock, or installing a recoil pad done before you mount the scope.
Let the bases, rings, screws, and receiver dry for 30 minutes.
If your scope has integral bases (bases that are a permanent part of the receiver) and you intend to attach ringmounts directly to the integral bases without attaching additional bases, you can proceed to the next part in this article about attaching scope rings to the bases. You must attach scope bases to your rifle if it does not have integral bases.
Check The Scope Bases
Hold the base or bases on the receiver.
If you will be mounting Leupold® QR™ (quick-release) bases, position the bases so the locking levers are on the left side. Most one-piece bases can be installed in only one direction.
If the screw holes through the base do not align with the screw holes in the receiver, try turning the one-piece base around or exchanging two-piece bases between the front and rear positions.
If one of the bases or one end of a one-piece base is thinner than the other, the thinner base or thinner end goes over the front receiver ring.
Look through the base screw holes to be sure they are aligned with the screw holes in the receiver.
If you are installing a two-piece base, orient each base so the rings will be at the most forward positions when attach. (i.e., both of the cross-slots should be forward if you are installing cross-slot bases.)
If you are installing two-piece, rotating-dovetail (Redfield-type) bases, the lug recess and the lateral screws should be forward on their respective bases.
(That will help get the maximum eye relief initially when you install the scope. You may have to turn at least the front base around later if the scope tube is too short to span the distance between the rings, but try mounting the bases so both rings will be at their most forward positions for now.)
The screw holes will align if you ordered the correct bases for your rifle model and length of receiver and if you place each base in its correct position.
You may have the wrong bases for your rifle if all the screw holes do not align no matter how you position the bases.
Do not attempt to install any of the screws if all the holes through the base do not align with all the screw holes in the receiver.
Bases are not returnable or exchangeable if the base finish or screws have been marred.
Attach The Scope Bases
If the screws align correctly, use a lint-free cloth such as a bore cleaning patch to apply a thin layer of fresh gun oil to the top of the receiver and to the bottom of the bases.
Apply just enough oil to protect the metal. Do not apply so much oil that the bases float on the oil.
Put the correct size hex or Torx bit in your bitdriver now.
Install all of the base screws.
The long screws go through the rear base if some of the screws are longer than others.
Just snug the screws for now; do not tighten them.
After each screw is snugged in its respective position, Tap the rear base forward several times with a mallet. (Use a mallet - not a hammer - to prevent marring the scope base.)
Lightly tap the base forward; not backward.
Do not try to shear the screws.
Five light taps should be enough.
Now tighten the rear screw - just the rear screw for now. Tap the base forward five more times.
Tighten just the rear screw again. With the tip of the hex bit or screwdriver in the screw slot, tap downward on the grip end of the screwdriver with the mallet as you apply continuous light tightening torque; 10 solid taps to settle the screw in.
The scope base screws are normally size#6 so do not over tighten them.
Over tightening will shear the screw shank off in the screwhole or strip the slot in the head.
Apply light torque and let the downward tapping settle the screws. (Do not tap the end of a calibrated torque wrench such as the Wheeler FAT wrench; you will knock it out of calibration. If you have an FAT wrench, use it to check that the final torque is 25 inch-pounds instead.)
That was just the rear screw so far.
Now attempt to gently close the gun action. Gently. Stop if the action will not close or if you feel any binding.
The scope base screws may be too long if you feel binding or resistance. Base screws will not protrude through the receiver into the bolt passage if you have the correct bases for your firearm and install the screws in their correct holes. But it is better to find out now than later.
Working forward, tighten the other screws in the same manner - five forward taps, tighten, five more taps, then 10 downward taps while tighten.
Operate the action after each screw has been tightened to check for binding. The last screw to be tightened should be the most forward base screw.
Did you tighten all the base screws? Good. Now rap the bases forward with a mallet a little harder than the forward taps earlier.
Ten good solid raps to simulate the rifle recoiling rearward beneath the scope.
(In reality, the rifle will recoil rearward beneath the scope. Scope base screws will often need to be retightened after the first five shots or so after which they will stay tight. Simulate recoil with a mallet and get the retightening out of the way now.)
Then go back to that first screw you tightened; the rear one.
Working forward again, give each of the screws five more downward taps while you apply light tightening torque.
(If you ever have to remove the base screws, tap downward on the screwdriver grip while you apply loosening torque.)
Slowly and gently close and open the action again a few times. Feel for any binding or resistance.
That was how you mount the bases. It was easy. Most types of scope bases can be attached to the receiver as described above.
However, each type of scope rings attach to their bases differently.
Now you complete mounting a scope base to the rifle. You will attach the rings to the bases next.
Attach The Rings
The previous part was about attaching scope bases to the rifle receiver. Now you can attach the scope rings to those bases. Be careful; each style of rings attaches to its bases differently.
Check The Rings
After the scope bases have been attached to the rifle receiver, the next step to mount a scope is to attach the rings to the bases.
Be certain the scope rings are the correct size and height to accommodate your scope before you install them onto the bases.
Scope rings are not be returnable or exchangeable if they have been marred.
So do a preliminary check of scope ring height and size before you install the rings to determine whether or not you have the correct rings before you waste time and effort trying to install the wrong rings and risk marring the finish in the process. It will take only a few minutes.
Obviously the ring attachment system must be compatible with the bases installed on the rifle. (e.g., rotating-dovetail rings for rotating-dovetail bases and cross-slot rings for cross-slot bases.)
Also, the size of the rings must match the diameter of the scope tube. (1-inch rings for a 1-inch scope tube, 30mm rings for a 30mm scope tube, etc.)
If the rings are the correct size and type, place the rifle in the gun cradle or sight-in vise and open the action.
Remove the ring half screws and set both ring caps (the top halves of the rings) aside.
Loosen both ring clamp screws completely if they are cross-slot Weaver-type) rings. Remove the lateral screws from the rear base if you have single rotating-dovetail system (Redfield-type).
Turn the lever on the left side of the bases rearward if your rifle has quick-release bases. Loosen all the clamp screws if you have ringmounts for integral bases.
Install the lens caps on the scope.
Carefully place only the bottom half of the rings on their respective bases.
Position cross-slot rings at the most forward cross-slot on their respective bases.
Do not tighten the clamp screws on cross-slot rings and do not throw the locking levers on quick-release bases yet.
If the stem of one ringmount is longer than the other, the ringmount with the longest stem goes on the rear base.
Support the dovetail lug of the front ring of a rotating-dovetail system along the left side of the front base and hold it there with your fingers because it will not stay there by itself.
Carefully place the scope in the rings so you do not knock the ring bottom halves off the bases.
Slide the scope forward in the ring saddles as far as the power ring or eyepiece lock ring will allow.
Viewing horizontally from either side, does the bottom of the objective lens bell with the lens caps installed appear to be at least 3/16-inch above the top of the rifle barrel or rear sight?
The rings are too short if there is not at least 3/16-inch of clearance between the objective lens cap and the rifle barrel (or rear sight).
(Later, when you tighten rings, the clearance could be drawn down as close as 1/8-inch. For now, look for at least 3/16-inch of clearance.)
Without disturbing the scope, slowly close and reopen the action. Is the ocular lens bell with its lens cap installed high enough to clear bolt handle if the rifle has a bolt action?
Will the ocular bell interfere with the operation of the safety lever? If the rifle has a hammer, can the hammer easily be cocked and decocked?
It is better to discover any interference now than after you install the rings.
Order higher rings if the ocular lens cap impedes the operation of the action or if the objective lens cap appears to be less than 3/16-inch above the barrel or rear sight. Higher rings have longer stems to mount the scope higher.
Attach The Rings
Attach the scope rings to the scope bases only after you determine the rings are the correct size and height. Quick-release, quick-detach, cross-slot rings, and rotating-dovetail rings each attach to their bases differently. Ringmounts attach directly to integral scope bases. Some of the most common scope ring attaching methods are described below.
Leupold® QR™ (quick-release) rings have a stud under the stem of each ring that is inserted into a special base. A thumb lever located on the base is rotated to lock each ring onto its base. As their name implies, quick-release rings are easy to release from their bases; and they are almost as easy to attach.
According to the previous part in this article, the bases should have been installed with the locking levers on the side opposite the ejection port. Rotate both locking levers rearward. Wipe the ring studs with gun cleaner-degreaser. Orient the rings so the locking grooves in the ring studs are rearward. Insert each of the ring studs into its recess in its base and rotate the locking lever on the side of each base up and forward to draw the rings down and lock them. The rings are attached. Easy, huh?
Quick-detach rings are scope rings that clamp to standard cross-slot bases by tightening thumb levers located on the rings themselves.
They are almost as easy to attach to their bases initially as they are to detach.
Turn the thumb levers of both quick-detach rings fully counterclockwise to open the jaws.
Wipe the cross-screws and the insides surfaces of the ring jaws with a gun cleaner-degreaser patch to remove crud.
Also wipe the cross-slot and rails of the bases.
Orient both rings so the levers will be on the side opposite the ejection (usually the left side).
Place the rear ring in the closest cross-slot behind the ejection port. Turn its thumb lever clockwise to clamp the jaw to the base.
The lever may require several turns or as little as 1/2 turn to tighten depending on the brand and style.
Place the forward scope ring in the forward-most cross-slot.
(If you discover later that the scope tube is too short to span between the rings, you can quickly detach the front ring and reposition it a slot or two rearward.)
Tighten its lever by turning counterclockwise also.
Lightly tap the fixed jaw side of each ring toward the receiver a few times with a mallet to settle them onto their bases. Then try to turn the thumb levers tighter.
If the thumb levers tightened any more, lightly tap the fixed jaw side again and try to re-tighten the levers.
With any luck, the levers will be pointed rearward when the jaws are tight so they will be less likely to loosen if snagged on a branch while hunting.
The thumb levers of some brands of quick-detach rings such as Warne® Maxima™ rings can be repositioned out of the way after tightening without loosening the jaws.
Cross-Slot Rings & Tactical Rings
Cross-slot (Weaver-style) rings, of course, attach to cross-slot bases.
Loosen the nuts or screws (whichever your rings have) on the cross-slots and open the clamp jaws.
Wipe the cross-slots and the rails of the bases and the cross-screw and inside surfaces of the ring jaws with gun cleaner-degreaser to remove gunk.
Position each ring at the forward-most slot on its respective base for now. (You can reposition the front ring a slot or two rearward later if you discover the scope tube does not span between the rings.)
Align the cross-screw or the recoil tab with a cross-slot. Whether your rings have nuts or screws, both nuts or both screw heads should be on the same side.
Position the nuts on the side of the receiver opposite of the ejection port so the nuts will not interfere with case ejection.
(Position the nuts on the left side if your rifle ejects to the right; on the right side if your rifle ejects to the left.)
Turn the nut (or screw) on each ring clamp until the rings are tight on the bases.
Lightly tap the fixed jaw side of both rings toward the receiver a few times with a mallet to settle them onto their bases. Now tighten each ring to its base just a bit more.
(Just a little tighter than snug. Do not over tighten. Over tightening will strip or shear the cross-screws.)
Tap the end of the screwdriver or nutdriver with a mallet as you apply light tightening torque.
Tap the fixed jaw toward the receiver a few more times and re-tighten the nuts without over tightening them. That is how you attach cross-slot rings.
Ringmounts attach to integral bases in one of several ways depending on the model of rifle.
Some ringmounts have a fixed jaw on one side and a clamping jaw on the other side.
Both jaws clamp on another type. A third type of ringmount has a dovetail recess underneath that slides onto an integral dovetail rail on top of the rifle receiver.
No matter which type of ringmounts you have, wipe the integral base recesses or grooves and the ringmount jaws with a cleaning patch wet with gun cleaner-degreaser.
If your ringmounts have one fixed jaw each, loosen the clamping jaw of both ringmounts, orient the ringmounts so both nuts are on the side opposite the ejection port, and insert the fixed jaws into one of the grooves on the receiver.
Be certain the fixed jaws are squarely in the grooves or recesses then tighten the clamping jaw of each ringmount.
Lightly tap the fixed jaw of both ringmounts toward the receiver with a mallet to settle the jaws into the groove.
Try to re-tighten the clamping jaws after you tap the fixed jaws into the grooves.
Alternately tap the fixed jaw and tighten the clamping jaw until the clamping jaw will not tighten anymore with light torque.
Ringmounts for Sako® centerfire rifles slide onto integral dovetail rails on top of the receiver.
The ringmount with the recoil pin attaches to the rear base and must be slid forward onto its rail from the rear.
Loosen the clamping screws and slide each ringmount onto its respective integral base.
The clamping screws of both ringmounts should be on the same side.
The rear ringmount can only be placed in one location on its rail due to the recoil pin. The forward ringmount should be placed about 1/4-inch behind the forward end of the front integral base for now.
You may have to slide it rearward later to accommodate a scope with a short main tube later. Tighten the clamping screws to secure each ringmount to its base.
Ringmounts that fit Ruger® rifles have clamping jaws on both sides and a recoil tab under the stem.
Tighten both jaws of each ringmount completely before you try to put the ringmounts on the bases. Now evenly loosen each jaw one turn at a time alternating between sides until you can just slip ringmounts onto the integral bases.
If one ringmount has a longer stem than the other, the ringmount with the longer stem attaches to the rear integral base.
Be certain the recoil tab of each ringmount goes into its recess. Now tighten the jaws 1/2-turn at a time alternating between sides while holding the ringmount in position.
Alternate 1/4-turns when the jaws become snug.
Tap the ringmounts stems lightly from side to side with a mallet to settle them.
Then try to re-tighten the each jaw no more than 1/8-turn before tightening the other side. Tap the ringmount stems from side to side then attempt to re-tighten the ring jaws.
Attach the rear ring first if you will be installing a dual rotating-dovetail system.
If you are installing a single rotating-dovetail (Redfield-style) ring, install the front ring first.
Do not use the scope to turn rotating-dovetail rings into position.
The ring will have considerable resistance to rotation which may damage the scope.
Instead, use a 1-inch scope ring lapping bar or a 1-inch wooden dowel to turn 1-inch diameter rings.
Use a 30mm scope ring lapping bar to turn 30mm diameter rings.
Loosen the ring cap screws just enough to slip one end of scope ring lapping bar or dowel through so it protrudes about 1/4-inch out the other side.
Tighten the ring cap screws to grip the bar.
Apply gun grease to the sloped surfaces of the dovetail lug and to the bottom of the ring stem.
Insert the dovetail lug into the dovetail recess. (Remember, if you are installing a dual dovetail mounting system, install the rear ring first.)
The bar or dowel should be perpendicular to the rifle and base at this point.
Now, hold the rifle down with one hand and swing the bar 90 degrees so it is aligned over the receiver and barrel.
Considerable resistance is normal. Swing the bar an additional 15 degrees or so past the barrel and receiver.
Then swing it back over the receiver and barrel. Align the bar precisely over the receiver and barrel.
Loosen the ring cap screws and slide the bar from the ring. Wipe excess grease from the top of the base.
Attach the front ring the same way if you are installing a dual rotating-dovetail mounting system.
After both rings are installed, span the rings with the ring lapping bar and tighten the rings around the bar.
Tap both sides of bar near each ring with a mallet several times to align the rings with the lapping bar.
Re-tighten the ring cap screws and tap both sides of the rings again. Continue to tapping the bar with a mallet then re-tightening the ring cap screws until the screws will not tighten more.
The rings will be in lateral alignment when the ring cap screws will not tighten any more. Remove the ring caps and remove the lapping bar.
Attach the rear ring now if you are installing a single rotating-dovetail system. Loosen the cap screws of both rings. (The front ring should already be attached to its base as described two paragraphs above.)
Loosen both laterally opposing windage screws of the rear base. Place the bottom of the rear ring stem flat on the top of the rear base. Span the bottom halves of the rings with the lapping bar.
Tighten the front ring around the bar first. Slide the rear ring forward or backward on its base until the crescent-shaped recesses in the ring stem are aligned with the windage screws.
Turn the windage screws until the screw heads lightly engage the recesses in the stem.
Be certain the bottom of the rear ring stem is flat against the top of the rear base then tighten the rear ring around the lapping bar.
Snug both windage screw heads to the rear ring stem. Center the rear ring on top of the base by first loosening one screw and tightening the other. Remove the ring caps and remove the lapping bar after the rear ring is centered and the windage screws are tight.
That was how to install scope rings onto the bases. Now you can install the scope into the rings. Installing the scope in the rings is the subject of the next part is this article.
Install The Scope
Do not give up yet. Installing the scope into the rings is the final task of mounting a riflescope. You can be certain your scope is installed correctly if you install your scope as described in this article.
Mounting a scope involves attaching the bases to the receiver, attaching the rings to the bases, and installing the scope into the rings.
By now you should have attached the bases and rings according to the two previous part in this article - Attach The Bases and Attach The Rings. Installing the scope is the final task for mounting a scope. That is what this article is about.
Actually, you must check for scope fit before you install the scope into the rings. This step applies to all types of scope mounting systems.
Check Scope Tube Fit
Remove the screws that hold the ring caps on the ring saddles. Set the caps aside so you will know which cap mates with whichever saddle later. Place the scope in the scope ring saddles.
Does the scope tube fit into the saddles of the scope rings? A 30mm tube will not fit into 1-inch rings and a 1-inch tube will be too loose in 30mm rings.
Will the scope span the distance between the scope rings?
If scope does not span the distance and the bases are cross-slot tactical bases, remove the front ring and reinstall it at a different cross-slot.
Slide the front ring rearward so there will be at least a 1/8-inch space between the front ring and the objective lens bell if the front base is a dovetail rail.
Replace the front ring of a rotating dovetail system with an extension ring if the scope tube will not span between the rings.
Check Ring Alignment
The bores of the scope rings must be aligned with each other both vertically and laterally.
Tightening the scope ring top halves (the caps) around a scope seated in either vertically or laterally misaligned rings will cause the scope to bend.
The scope will twist if the scope rings are tightened in rings that are both vertically and laterally misaligned.
Scope internal mechanisms are assembled with such close tolerance that bending or twisting the main tube will stress the delicate lenses, springs, and screws inside the scope causing malfunction or permanent damage.
Severe ring misalignment could scratch or kink the main tube, distort the seals, crack the lenses, interfere with the windage and elevation adjustments, and damage the power changing mechanism.
Do not damage your riflescope with misaligned rings.
Some brands and types of scope rings include alignment inserts that pivot universally within the rings.
The inserts bear on the scope main tube and pivot within the rings to compensate for slight ring misalignment rather than bending or twisting the scope tube to the rings.
If your scope rings do not include pivoting inserts, ring alignment is easy to check with a set of scope ring alignment bars or rods.
Use 1-inch bars to align 1-inch rings and 30mm bars to align 30mm rings. One bar is installed in each of the rings with the pointed ends toward the middle.
Ring alignment is indicated when the points are aligned.
You'll be able to determine lateral alignment by looking straight down from above.
Rotating dovetail rings can be rotated or windage screws turned to correct lateral misalignment.
Vertical alignment is determined by viewing relationship of the points horizontally.
Vertical misalignment of more than 1/16-inch can be corrected by inserting a shim of the correct thickness under the low base of a two-piece base and a bit of scope ring lapping.
(Do not fret; correctly installed scope bases and rings rarely have more than 1/16-inch of misalignment.)
Vertical misalignment of less than 1/16th-inch can be corrected by lapping the scope rings. (That is no more than 1/32-inch of lapping required per ring.)
Do not lap the scope rings into alignment yet; you must be certain the rings are compatible with your rifle and scope before you lap them.
(Scope rings are not returnable after they have been lapped.)
Ring height is one more factor that must be certain.
Ring height affects the objective bell clearance above the barrel and the clearance of the bolt handle below the ocular bell on bolt-action rifles.
The scope's longitudinal position within the rings will also affect scope clearance because the eyepiece and the objective lens bell are at opposite ends of the scope.
Because eye relief is adjusted by sliding the scope forward or backward in the rings, you must adjust eye relief before you can be certain ring height is adequate.
Adjust eye relief now.
Adjust Eye Relief
Eye relief is the distance from the ocular lens a viewer's eye must be to see the full field of view (FOV).
You must adjust eye relief to fit yourself.
Read How To Adjust Eye Relief Correctly on this website for more information about eye relief and how to adjust it.
Be sure the objective lens end is toward the muzzle. Since you should set eye relief close to its forward limit, position the scope as far forward in the saddles (the bottom half of the scope rings) as power adjustment ring or the eyepiece lock ring will allow.
Place the ring caps (the top half of the scope rings) over the scope tube and install the screws.
Do not tighten the screws because you must slide the scope rearward within the rings to adjust eye relief.
Will you be wearing heavy clothing when you hunt? Will you be wearing a recoil pad?
The thickness of your coat will affect eye relief. So will a recoil pad.
Put the heaviest clothing on to adjust eye relief that you will be wearing when you go shooting.
Remove the lens caps. Set the power at its highest magnification if the scope has variable-power.
The highest power setting will provide the shortest eye relief range. You can adjust eye relief for the lowest power setting later if you have a variable power scope.
Do not be concerned with focusing or leveling the reticle yet.
With the rifle unloaded and on 'SAFE', pick up the rifle, point it at a light-colored featureless wall, close your eyes, and assume your shooting position.
You must adjust the eye relief to fit you; do not adjust you to fit the eye relief. So do not crane or scrunch your neck. Just assume a comfortable shooting position.
Relax. Now, maintaining that comfortable shooting position, establish a good stockweld.
Now you can open your aiming eye. Do not change your head position. Attempt to view through the scope. What do you see? Do you see the whole field of view clearly the instant you open your aiming eye or do you see a shadow around the perimeter?
Slide the scope 1/8-inch or so rearward (toward you). Close your eyes, assume your preferred shooting position again, relax, and get a good stockweld.
Without changing your head position, open your aiming eye. Do you see any perimeter shadow now? If you still see shadow, move the scope another 1/8-inch rearward.
Continue sliding the scope rearward in 1/8-inch increments and checking until you do not see any perimeter shadow - none at all.
Close your eyes each time before you establish a stockweld so your are not tempted to crane or scrunch your neck.
Check the eye relief at least three times but as many you need to be certain there is no shadow.
When the scope is at a position where there is no perimeter shadow, slide it rearward one additional 1/8-inch.
At this position the scope should be about 1/8-inch within the forward limit of the eye relief range. Check the eye relief again at this final position. You should not see any shadow now.
Eye relief is adjusted if you do not see any shadow. Careful; do not move the scope.
Put the lens caps on. Remove the ring half screws and the ring caps being careful not to disturb the scope. Leave the scope in the ring saddles. Cut two strips of 1/2-inch wide electrical tape; each 3+1/8-inch long if your scope has a 1-inch main tube or each 3+5/8-inch long if your scope has a 30mm tube.
(Black electrical tape goes well with a scope that has a black surface finish. White electrical tape looks better on scopes that have a silver finish.)
Stick one end of each strip of tape on the scope main tube precisely where each of the ring saddles is located.
Pick up the scope and wrap each strip of tape all the way around. The tape will mark the eye relief position.
Place the scope back into the ring saddles. Align the electrical tape strips with the rings.Place the scope ring caps in position and install the screws.
Do not reinstall the ring caps yet; you still have to be certain the rings are the correct height for your scope and rifle.
Check Ring Height
Check ring height again now that you have adjusted eye relief. The lens caps should have been re-installed already. Press the scope tube down to the bottom of the ring saddles with hand pressure.
Operate the action. Check if the bolt handle will clear the ocular lens bell if it is a bolt action. If the action has a hammer, be sure it can be cocked and decocked without striking the ocular lens bell. Be sure the safety lever can be operated without if it has a thumb-operated safety lever.
Now check the clearance between the objective lens bell and the top of the barrel again.
With the rings securely attached to the bases, the clearance should be at least 1/8-inch with the lens caps installed.
It is better to be a just bit more than 1/8-inch than any less. However, the clearance between the objective lens cap and barrel should not be more than 3/8-inch.
If your rifle has a rear sight and the scope extends to the rear sight, the scope with lens caps installed must clear the rear sight by at least 1/8-inch also.
You must exchange the rings for some with longer stems if the objective lens cap clearance above the barrel is not at least 1/8-inch.
That is why you should not have lapped the rings into alignment yet.
Thread Locking Compound (?)
By now you should know whether or not the scope rings are compatible with your rifle, bases, and scope.
Would you like to permanently attach your bases to the receiver?
Thread locking compound will prevent the screws from loosening - even if you wanted them to loosen.
You will have difficulty removing the bases if you ever wanted to try a different scope base style.
Do you really want your scope bases to be permanently attached to your rifle?
Then remove the rings and bases and go through the process of reinstalling them after you apply a drop of thread locking compound to each scope base screw. (Apply thread locking compound to the scope base screws only. Do not apply thread locking compound to any of the ring screws.)
You could do all that if you really wanted to or you could simply be confident that you have installed the bases correctly so far.
Lap The Rings
Scope rings should conform to the scope rather than forcing the scope to conform to misaligned rings.
Vertical ring misalignment less than 1/16-inch can be corrected by lapping.
Even if the rings are in alignment, lapping will increase ring bearing surface on the scope tube and remove burrs from the rings that might scratch the scope finish.
Do not lap scope rings that include alignment inserts; let the insert serve their intended purpose. The inserts will pivot to align with the scope tube despite the rings being misaligned themselves.
If scope rings without alignment inserts are misaligned, a scope lapping bar of the correct diameter - a 1-inch bar for 1-inch rings or a 30mm bar for 30mm rings - is required to lap scope rings into alignment.
Lapping compound is applied to both ring saddles and the lapping bar is spanned across both rings.
Then bar is pressed and rolled into the lapping compound. The pressure points within the scope rings will wear away because the ring metal (aluminum or soft steel) is softer than the lapping bar.
Scope ring lapping takes some effort, but when it is finished the rings will be in nearly perfect alignment.
Follow the instructions included with the scope ring lapping kit.
Install The Ring Caps
Remove the lapping bar and thoroughly clean the lapping compound from the rings with gun degreaser.
Align the electrical tape around the scope tube with the ring saddles and place the scope back into the ring saddles. The tape will keep the rings from scratching the scope finish and will help the rings grip the tube so leave the tape strips around the scope tubes unless the tape interferes with the fit of the rings around the scope.
The elevation (up and down adjustment) turret must be on top with the windage (left and right) turret on the right side.
Place the ring caps over the scope tube. Be sure to return the ring caps to their original saddles.
Degrease the screws and just start them into the rings. Do not tighten the ring cap screws yet.
You may have to rotate the scope within the rings to level the reticle before you tighten the ring screws.
Level The Reticle
The vertical crosshair must be vertical and directly over the rifle bore for accurate shooting.
In other words, the reticle must be level. So how to level a scope on a rifle?
Scope leveling made easy. One method is to turn the power down to its lowest magnification, view a door frame or window frame through the scope, and align the vertical crosshair with the frame.
That works assuming you are actually holding the rifle level as you viewed the door frame. You may not realize you are canting the rifle.
Another method it to hang a carpenter's level horizontally on a 100 yard target frame at a shooting range and align the horizontal crosshair with it.
This method works only if you were not canting the rifle as you aligned the horizontal crosshair of the scope with the level.
Wouldn't it be nice to have some sort of device to indicate the rifle itself was actually level before you leveled the reticle to that rifle - one you could magnetically attach to your rifle?
Well, if you have a Wheeler Engineering® Professional Scope Mounting Kit™ you have such a device. It is include with the kit.
It is called the Level-Level-Level. (The Wheeler Engineering® Level-Level-Level™ can be purchased separately or as part of the Professional Scope Mounting Kit.) It actually includes two bubble levels.
The first one really does magnetically attach to the rifle. The second level is placed atop the elevation turret after the rifle has been leveled with the first one.
Without disturbing the rifle, the scope can then be twisted within the scope rings to center the bubble of the second level.
The horizontal crosshair of the scope reticle is level when the bubble of the second level is centered.
Final Ring Cap Tightening
The taped sections of the scope tube are aligned with the rings. The ring caps are on their respective ring saddles. The screws are started and the reticle is level.
You are almost done! All you have to do is tighten the rings around the scope main tube.
Do not use thread locking compound on the ring half screws. It is not needed there.
Tighten the rear scope ring half screws first. You have to tighten the left and right screws of the ring half evenly. The reticle may cant if you do not tighten the screws evenly. You can alternately turn the left and right screws one full turn initially.
Alternately tighten the screws only 1/4-turn when you feel the screws start to tighten. The torque of the left and right screws should feel about the same if you do this right.
Do not overtighten the screws. Just a bit more than snug. You do not want to shear the screws off. The rings halves should tighten around the scope tube before they tighten to each other.
Do not tighten the ring caps so much that they collapse the scope tube.
You should see a small space between the ring halves of horizontally-split rings. The spaces between the top and bottom halves should be about the same on the left and right sides.
The left and right sides of the ring have not tightened evenly if the spaces are not about the same or if one side of the ring has closed completely.
Tightening the rings unevenly may cause the scope to rotate and cant the reticle. You will have to loosen both screws completely, re-level the reticle, and tighten the screws evenly.
Assuming you tightened the rear scope ring halves evenly, you should verify the levelness of the reticle before you tighten the front ring half screws.
Is the reticle still level? Tighten the front ring half screws that same way you tightened the back ring half screws - evenly. Recheck reticle level. You are done if the reticle is still level.
That is how you mount a scope! See, it is not difficult. It just takes some time to do correctly.
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