DIY Scope Mounting

Not what you’re looking for? Find more articles on hunting gear!

With the right bases, rings, screws and tools, do-it-yourself scope mounting is easy. Follow a few simple steps and zeroing your new rig is straightforward. But miss a beat and you could be in for a world of frustration.


Few things get me more cranked up than bringing home a new rifle and new optics. The only challenge is trying to marry the two together.

For a moderate fee, gunsmiths will mount your scope for you. Theoretically, hiring a pro alleviates any confusion associated with parts and accessories. Then again, there is always the question of just how qualified is the gunsmith. With emphasis on the word qualified, I’ve seen many scopes incorrectly installed on rifles and this inevitably sets up the shooter for a world of impending frustration. An almost unlimited number of problems can arise when mounting a rifle scope, but most can be traced to selecting the wrong bases and rings for the particular type of firearm you are using.

Another problem frequently encountered relates to either over-tightening or under-tightening base or ring screws. Each manufacturer determines the precise inch-pound torque ratings most suitable for their products, and these must be strictly adhered to if you want to avoid damaging the riflescope.

Alternatively, as long as you have the correct rings, bases, mounts, screws and tools, and of course adhere to a few simple rules, do-it-yourself scope mounting can be simple and cost-effective. Follow these important steps and you’ll be set up in no time.


Prepare properly

Proper preparation will make your job easier.

First, consider where and how you want to work on your rifle and scope. A workbench or countertop provides an elevated surface. Safety should be your first priority and this means confirming that the firearm is unloaded and then disabling it, such as removing the bolt or otherwise disabling an alternate action.

A vice is best for securing the rifle in a manner that will allow you to work on it. With the rifle in place, you’re just about ready to go – all that’s left is gathering the necessary tools to do the job. You can collect all of the different wrenches, lubes and accessories separately, or purchase a scope mounting kit containing all of the requisite items.

Switching one scope for another requires less in the way of tools, but as a rule you’ll want to have a torque wrench and screw driver (with the necessary bits), thread locking compound, scope ring alignment bars, a lapping tool, lapping compound and a leveling tool (optional) for adjusting the scope for crosshair alignment. It’s a good idea to have a cloth and cleaning solvent handy as well.


Make sure you have the correct bases and rings

Have you ever gone to the range to sight in your rifle, only to find that your scope adjustments are maxed out and you still can’t get your rifle zeroed?

If you shoot different guns or are frequently setting up new firearms, chances are you have encountered this exact scenario. Believe it or not, it’s more common that you might think. Yes, regardless of whether you mount your own riflescopes or have a gunsmith do it, it sometimes happens. The best gunsmiths I know are well acquainted with this problem and usually know which bases and rings accommodate specific scopes.

Bases and rings come in a variety of shapes and sizes. Most have a top and bottom half, but some in fact clamp with a left and right vertical orientation. Two-piece rings and bases are each designed for specific rifles and scopes.

Before you begin, determine whether your rifle scope has a one-inch tube or a 30 millimetre tube, then talk to a qualified gunsmith about which bases and corresponding rings will work for your specific make and model of firearm. Don’t underestimate the importance of this step. The ones you choose will, at least in part, be based on the rail or other mounting-hole system available on your firearm. Equally important is the Range of Adjustment (ROA) of the scope you are mounting. The rings and bases must be able to accommodate the specific ROA of your scope.

With these in hand, you’re ready to proceed.

On new rifles, plug screws are usually found in the mounting screw holes. With the correct screwdriver in hand, stand directly over these holes and carefully remove them. As you remove or install screws, be intentional and cautious not to strip threads. Any time you remove screws, it’s smart to clean the holes with a degreasing agent.


Adhere to manufacturer’s installation instructions and torque ratings

Bases and rings usually come with written instructions. Take care to follow the manufacturer’s recommendations for placing and fastening these to the mounting holes.

Some gunsmiths advise not to use thread-locking compound, and still others insist on using it. This is a choice you will have to make yourself. If you do, be sure to use a purple or blue-colored thread locking compound and not red, to ensure that you can remove the screws at a later time. Screws should only be torqued to each individual manufacturer’s specifications. For example, I’ve seen torque recommendations base screws ranging from 10 to 30 inch-pounds for bases.

The next step involves attaching the front ring to the front base. With certain kinds of bases, this can be done with a wrench or the lapping bar.

By attaching the rings to the lapping bar and placing the front ring into the front base, turn it just past centre and then rotate it back to align with the rear base.

At this point, remove the lapping bar from the front ring and set the rear ring simply by removing one of the windage (or bottom) screws, setting the bottom half of the ring in place and then re-fastening it.

With that step complete, use the scope alignment bars to make fine adjustments to vertical and horizontal alignment to ensure the rings are true. It is absolutely imperative that these are in precise alignment. This generally requires some micro-adjustments to the windage screws. In some situations, lapping may be required. Lapping eliminates irregularities to increase the amount of surface area that the scope contacts, in turn minimizing the chances of your scope shifting as a result of repetitious shooting recoil.

If you choose to lap your rings, simply assemble them, apply lapping compound to the inside of the rings, slide the lapping bar through the rings, thread the handle in to the lapping bar and then evenly tighten the screws just enough to allow the bar to move with a little resistance. Most gunsmiths recommend lapping until 60 to 80 per cent of the ring surface is removed, but most importantly until the lapping bar moves back and forth freely. When this is done, be sure to clean all of the parts thoroughly.


Take care to accurately adjust and set your eye relief

When the bases and rings are in alignment, it’s time to set the scope in place and loosely set and re-fasten the rings around the scope tube. The most important step at this point is properly adjusting for the eye relief.

A good place to start is positioning the rear of the scope an inch or two back from the back of the trigger guard. With the scope set to its mid-range magnification, shoulder the firearm naturally, look through the scope and if the field of view is clear, chances are your eye relief is set properly or at least close to where it needs to be. If not, slide it forward then slowly back toward your eye until the first point at which the entire field of view is clear. Stop there. Try shouldering the firearm and acquiring a target several times to make sure that the riflescope is positioned correctly.


Rotate the scope to level the crosshairs

At this point, rotate the scope tube to level the crosshairs. This involves spinning the riflescope clockwise or counter-clockwise until the vertical crosshair matches the vertical axis of the rifle. You can do this by eyeballing it, but it can be helpful to use a reticle leveling tool.

With this fine-tuning done, use a torque wrench to tighten the ring screws to the manufacturer’s inch-pound specifications.

Remember it is imperative that you don’t over-tighten, as this can strip screws. Over-tightening can also crimp or add undue pressure to the tube and restrict the inner workings of the magnification and focus adjustments. Fail to tighten the ring screws enough and your scope may move in response to the recoil. Manufacturer’s torque specifications are based on precise measurements and must be adhered to.


Bore sight before heading to the range

With the scope mounted, the second-to-last step involves bore sighting. This can be done prior to sighting in with live rounds. Remember, this is not the same as sighting in your scope and rifle. Bore sighting merely allows you to adjust your windage and elevation settings to a near approximation of zero.

Done correctly, bore sighting will make fine-tuning efficient and easy at the range. With a keen eye, bore sighting can be done on bolt-action rifles, for instance, by removing the bolt and sighting through the barrel to the downrange target. These days it is common practice to use a mechanical or laser bore sighting tool.

With these steps complete, you will have successfully mounted and bore sighted your new riflescope.


Fine tune for accuracy at the range

The final step to consummating the new marriage between rifle and scope is to visit the range.

At the range, you can fine-tune for pinpoint downrange accuracy. The distance at which you zero your riflescope will depend on the calibre and bullet you are shooting, along with the distances and target species you will be shooting.

For example, with my 243 Win I like to zero the crosshairs dead on at 100 yards because I use this rifle most for coyote hunting. On the other hand, with my 7mm Rem Mag I am using a 3-18x Z6 riflescope. With this rig, I know my shots will be at larger game like deer and moose, at distances usually between 100 and 300 yards. I generally sight in to zero my rifle two inches high at 100 yards to facilitate holding dead on with my crosshairs at 200 yards.

As long as you follow these basic steps, DIY scope mounting is a breeze. After fine-tuning at the range, double-check screws and you’re set to go.

Join us on Facebook!

Do you like what you’re reading? Subscribe to Western Sportsman print edition today!

Find more articles on hunting gear!

This entry was posted in Gear, General, Hunting and tagged , , . Bookmark the permalink.