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How to Mount a Rifle Scope

Rifle with Scope

Mounting your scope correctly is incredibly important. If your scope and your rifle are not pointing in the same direction, even the best scope in the world won’t be much use. This causes many new gunowners to hire a professional gunsmith for mounting, but if you follow these steps exactly, there’s no reason you won’t be able to mount your scope to your rifle yourself.

Tools


First, gather the tools you will need to mount your scope. It’s best to have these specific items rather than standard tools to keep from damaging your scope.

  • Screwdriver bits: Different mounting systems will come with different types of screws. You may be working with Allen head screws, Torx head screws, or nuts. You can purchase a set of gunsmith bits for your screwdriver that will protect your fasteners as you do this installation, and any future adjustments you may need to make on your firearms. As opposed to regular screwdriver bits, gunsmithing bits are hollow-ground and will fit perfectly into the screw, reducing wear on the screw and the likelihood of stripping it or damaging your gun.
  • Torque Wrench: This is a simple, quickly adjustable wrench for your screws. The tight fits this wrench ensures will keep you from accidentally shifting something while you are mounting your scope. If you are doing a lot of mounting or working with a particularly sensitive scope, you may want to invest in a digital version.
  • Loctite: Medium-hold Loctite will keep your screws tight while still leaving you with the option to remove them later if you would like to replace your scope or remount it. Before using it, check your owners manual; some materials do not react well to Loctite, as it can increase the torq on your rings.
  • Bubble Levels: Use these to level the rifle and the scope to make sure your adjustments are exactly in line with your rifle.
  • Rubbing Alcohol: Make sure to clean all of your materials with rubbing alcohol to ensure they are free from oil before you mount.
  • Cleaning Patches: Use these to clean parts prior to mounting.
  • Dial Caliper: This is an easy way to determine whether the scope and rifle are square. They come in digital and analogue versions.
  • Gun Vice: A gun vice will keep your rifle steady as you work on mounting your scope. This will make the entire process significantly easier.

Before You Start


Plan where you will mount your scope. It’s best to mount your scope as low as possible. This makes your firearm more portable, and makes it easier to put your eye on the scope axis. You may need to mount your scope higher if you have a large objective lens.

Double check the eye relief of your scope, and check the smallest one if you are using a variable scope. Make sure will be able to look into the scope easily at an appropriate distance. For most scopes, the eye relief is 3-4 inches.

You’ll also need to focus the eyepiece and reticle. Pointing the scope at a nearby uniform surface will help you see the reticle clearly. If you focus in low light, then the reticle will be sharp throughout different light conditions.

Finally, double check that your gun is unloaded (remove the magazine entirely to be sure) and your work area is clean and safe.

Now, you’re ready to get to work!

Step 1: Match Rings and Bases


Many modern rifles have grooves for mounting attachments, or are pre-drilled for scope bases. Make sure that you have selected the right mounting system for your rifle, and that the rings are the correct size (diameter and height) to position your scope correctly.

Step 2: Mount Bases


Mount the scope as low as possible on your rifle without the object lens connecting with the barrel. Start by cleaning all surfaces with rubbing alcohol to be sure they are free of oil. Check that you have aligned the bases properly, and that nothing is backwards.

If you have bases or rings of different sizes, consult the manufacturer instructions to make sure you are using the correct ring sizes in the correct positions.

Step 3: Attach the Bases


Then, use your Torque wrench or socket head to attach the bases and rings to your rifle. Unless your manufacturer advises against it, use your semi-permanent Loctite to attach the screws even more securely.

To make sure your bases attach evenly, tighten the screws alternately. If you are using rings attaching to the front base by a rotating socket system, make sure you use a wooden dowel to tighten the rings, not the scope itself. Be careful not to overtighten the screws, which can lead to stripping threads or breaking heads. You want at least four threads engaged in the receiver taps.

You may need to file your rings lightly if there are any burrs left from the manufacturing. Filing will keep your rings from scratching the tube of the scope. You also want to make sure the ring edges are parallel with the main tube; misaligned rings can result in damage to your scope.

The manufacturer instructions will recommend what torque each screw should be screwed in at. You can use your Torque wrench to make sure you are using the correct specifications.

Step 4: Align the Reticle


Now, the bottom half of your rings are in place. The next step is to attach these materials to the scope itself.

Place the scope in position, and tighten the top halves of the ring just enough so that the scope is in place but can still move. Holding your rifle level (ideally through the gun vice), rotate your scope until the reticle sits perfectly on the vertical and horizontal axes.

To be extra sure you are aligning the reticle correctly, use your bubble levels and dial caliper. One level should sit on the action of the rifle to ensure your rail is level. Then, use the rail of your dial caliper to attach to the bottom of the magazine well, and place the second bubble level on the rail of the caliper.

Step 5: Adjust Eye Relief


Now, check that the scope is in the correct position so that you can see the full image without being in danger of your scope hitting you in the eye when you fire your rifle. Your scope should tell you the specific eye relief needed, though most will be 3-4 inches from your eye.

If you will be wearing glasses when you’re shooting, make sure to wear them as you are setting up the eye relief. Your field of view may be altered even by non-prescription glasses worn for safety.

Pick up your gun with your eyes closed and put it into position. When you open your eyes, do you have a full view through the scope? If not, move the scope back and forth until you have a full vision.

Step 6: Tighten Screws


Now, check that the scope is in the correct position so that you can see the full image without being in danger of your scope hitting you in the eye when you fire your rifle. Your scope should tell you the specific eye relief needed, though most will be 3-4 inches from your eye.

If you will be wearing glasses when you’re shooting, make sure to wear them as you are setting up the eye relief. Your field of view may be altered even by non-prescription glasses worn for safety.

Pick up your gun with your eyes closed and put it into position. When you open your eyes, do you have a full view through the scope? If not, move the scope back and forth until you have a full vision.

Step 7: Test Your Sight


Now, you’ll need to make sure that you have mounted your scope correctly. In other words, you want to make sure that your scope is accurately predicting the placement of your bullet.

One way to do this is bore sighting. Insert a bore sight based on the caliber you’re using, and then adjust the vertical and horizontal axis based on your point of aim. This is best done at 25-50 yards, and tells you whether your scope and rifle are aligned in theory.

The only way to make sure your rifle and scope work well together in the field is to fire test rounds. Make sure you do this at home – you don’t want to discover your scope was improperly mounted in the middle of a hunting trip!

First, set your rifle up with a solid rest. You want to eliminate human error to focus on the success of your scope. Anything from firm sandbags to a benchrest will work.

Then, fire a few unloaded rounds and note whether the reticles move on your target. This will help you get used to your new scope. Then, fire one bullet and note where it lands on your target. Use your scope’s adjustments until the reticles are directly over the previous bullet hole. Finally, fire another shot at the bullet hole. If it goes to the exact same spot, then this is your zero. Set your scope to reflect this zero.