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Last Updated: October 25, 2020
For a simple and quick tutorial on the basics of mounting and sighting-in your new rifle scope, look no further.
You'll learn all you need to know from the necessary jargon to the anatomy of a scope to get the best tips before heading out to the field.
Without wasting anymore time, let's get started on mounting a rifle scope before moving onto instructions for sighting in a rifle scope.
How to Mount a Rifle Scope
This can be a tricky process, but with a little know-how and some help from your scope manual, you might just learn how to mount a scope without an issue. Here, we'll discuss some basic instructions, and then we'll go over some scope adjustments once you've successfully mounted your scope.
Getting started - A gun vise might come in handy for mounting your rifle scope. You'll need a clear, well-lit area and maybe some degreaser and oil. You might also need specific tools such as a screwdriver, socket heads, Torx wrenches, or even Leupold's ring wrench. You can remove all the filler screws that came with the scope with the screwdriver, and if it's called for, degrease mounting parts.
Double check that you have the right type and size mounting rings and bases. The scope should come with pre-drilled holes or grooves for your mounting system. Mounting rings can come in either one piece or two piece mounts. One pieces are typically easier to install because they're already pre-aligned with the base. Two piece rings usually require you to use a scope ring alignment tool.
You'll need to install the base and then the mounting rings according to the mounting system you have onto the barrel of your rifle. Typically it's going to be either the Weaver, Picatinny, or Dovetail system of some kind. The base goes on first, and then the lower half of the mounting rings. Make sure you're putting them on in the right direction, as low as possible while still allowing for clearance, and with a slight coating of oil for rust prevention. You also want to tighten each screw a few turns and then move on to the next one.
Lower the scope into the lower rings to be mounted. Then place the top rings on top to be snugly screwed into place. Following the torque recommendations for your scope is important since you can unintentionally overtighten the rings and cause damage to your scope. You will also need to take care to tighten the screws in a criss-cross, alternating pattern. This keeps the ring tops evenly depressed from side to side helping to ensure the scope tube will not be twisted in place once you have completed the tightening. It may be helpful to use a torque wrench to complete this process but before tightening too much, be sure to check your eye relief.
If your firearm has a large amount of recoil, shoulder the rifle and raise the scope to the eye to check for eye relief. You'll want to make sure that you don't leave the range with "evidence" (perhaps, a black eye) indicating you rushed through the mounting process. If there's enough eye relief, finally tighten the screws into place. If not, slide the scope forward within the rings until you have your preferred distance and then tighten the screws. Voila!
For a complete demo on how to mount a scope check out the video from Midway USA below:
How to Focus a Rifle Scope
Once you've installed your scope, you're now ready to focus your reticles. This part is to get the sharpest and clearest image of the reticle cross hairs for your eyes. Most rifle scopes come with an adjustable eye piece, and some even come with a locking mechanism to keep it from being accidentally bumped and throwing off the focus. Aim the scope at a blank backdrop.
For variable magnification ranges, use the magnification range that you want and that gives you the sharpest cross hair image. Fast focus eyepieces just need a fraction of a couple turns to get into focus. Once you've focused your reticles, this shouldn't need to be done again unless someone changed it. Now, all other scope adjustments can be made from here.
Understanding Scope Adjustments
There are three common scope adjustments that every rifle scope user should know about: windage, elevation, and parallax. Being able to have an intimate understanding of how your rifle scope works can give you the power to maximize the most out of your rifle.
Most American-built rifle scopes will have scope adjustments in increments of MOA, while a lot of European-built scopes will have adjustments in increments of Mrad. More commonly, these scope adjustments can be made with a dial or knob that has these increments on them that put the reticle in target with your point of aim.
These knobs are called target or scope turrets. Sometimes scopes don't come with turrets and instead it has a unique design where it can only be changed with specialized tools, and they typically have a cover to protect them from weather and rust.
MOA - Minutes of Angle or Minutes of Arc. Scope adjustments are typically set for 100 yards and is equal to 1.04 inches. Most rifle scopes come in either 1/4" or 1/8" increments. As a rough example, each click of the turret will equal 1/4" in distance at 100 yards. It's said like this, "Quarter (1/4) minute clicks".
Mrad - Milliradian. Scope adjustments are typically set for 100 meters. Most of these European styled rifle scopes will come in 1/10 Mrad which will translate into 1 cm for each click.
- Windage - This scope turret is typically installed on the side of the scope. It moves the reticle into line with your point of aim horizontally - left and right.
- Elevation - This scope turret can be installed on top of the scope. It moves the reticle into line with your point of aim vertically - up and down.
On paper, this all sounds very precise, since you have the basics of doing some serious math all in the click of small turret. But, not all scopes are calibrated to be exactly precise to the inch.
The accuracy of your scope and rifle and how it will actually perform is to be determined on the range. You might find that you only need to click two times instead of three to get right on target.
If you need to adjust to the left a little, it might pay off to over-adjust all the way over to the left and then come back to the right get it spot on. Getting to know your scope, rifle, and ammo takes practice, practice, practice.
These days, most rifle scopes are being factory-set to compensate for parallax at ranges of about 100 to 150 yards so that you don't have to tinker with that at all. That also means that it won't come with an external adjustment like a knob to enable you to manually adjust for it if you needed to.
If you're into very long range hunting and you'll be using magnification of greater than 8X, it might be worth it to you to buy a rifle scope with adjustable objectives or some sort of external adjustment feature like a side focus to compensate for parallax.
Air gunners who want closer range shooting than factory settings of 80 to 100 yards will want a parallax adjustment feature too.
A quick review - what's parallax? Parallax occurs when the reticle isn't on the same optical plane as the target image. Every time you move your eyes or head to a different angle, the reticle will appear to float or move from your point of aim.
The parallax adjustment is usually a dial that is marked with distances in increments. If your reticles are on target and crisp, move the parallax dial very slowly while moving your eyes and head up and down until the reticles stay on point and there is no more movement.
For more information on Parallax Adjustments check out our 27 Tips to Mastering Rifle Scope Parallax article.
For even more information about Parallax, check out the GunTalk.tv video with Leupold below:
How to Sight in a Rifle Scope
So, now you have your new rifle scope mounted and ready to go. What distance should you sight in... 25 yards, 100 yards? What type of ammo should you sight-in with? How many steps do I actually need to zero my rifle scope?
Many people believe that sighting in can be difficult and it's a complicated process. Not true. Although it does take some fine-tuning and experience, practice, practice, practice can be the key.
Some manufacturers factory-set their rifle scopes to be zeroed before being packaged. Even if this is the case, it's always best to double check before use. Whenever you get a new rifle scope, a new rifle, or some new ammo, be sure to properly sight it in before testing it in the field.
If you don't, you might yet have your new favorite sighting in screw-up or misplaced shot yet to come.
Why Sight In?
Good hunters want to hit their targets, and they especially want to have well-placed, ethical shots. Sighting-in is to align the the rifle scope's reticles with the bore of a rifle.
Quick tip for beginners - the bore is the interior of the barrel that the bullet comes out of. Well, sighting-in and accuracy are two different things. Accuracy simply refers to how well a rifle can perform shots in repeated succession close to each other.
Sighting-in refers to being able to predict where the shot will strike at known distances. Consequently, you improve accuracy when you sight in your scope. Well, at least, that's the point.
What Can Affect Accuracy and Sighting-In?
Ever wondered why an accurate rifle will miss the target? Or, if you have sighted it in but you still cannot produce tight groups? Ammo and gravity. Bullets come in different sizes, weights, and quality, but they're all susceptible to gravity.
Sighting in will help to determine how much of a drop the bullet will have over a known distance, thanks to the pull from gravity. You can then adjust your scope for bullet drop to ensure you make the bulls-eye.
Get Some Equipment
Before you even get to the range, make sure you have the comfy and secure equipment to properly zero your rifle scope. Some equipment to use can be:
- Kitty litter or dog food bags
- Sand bags
- Shooting rests/gun rests
- Tripod shooting rest
The whole point about getting an agreeable environment to sight in, isn't just for your comfort. It's for your firearm as well. Depending on what it is and your ammo, your rifle might prefer a softer surface than a harder one to absorb some of the bounce.
Remember, your forearm might also have more bounce if it's on a very hard surface. Some firearms can be picky with different degrees of firmness, so play around with what type of rest or sand bags reduce as much bounce as possible. A hard surface can produce a bounce that could send your bullet strike three inches high.
Bore sighting is done before you actually sight in your rifle. Bore sighting is done at 25 yards, and it is defined as lining up the barrel with your optics. Sounds just like sighting in right? Not yet, so stay with me. To make sure the bore of the barrel is in line with the optics, there are several ways you can do this. One way is to use a boresighter.
These can be either a laser type that shows where the barrel is pointing, or you can use a type of optic that gets inserted into the bore and you can view the image through the rifle scope. There are also other alternatives such as removing the bolt from your bolt-action rifle and then looking straight through the bore at your target and adjusting the scope to align.
Bore sighting is getting the bore in line with the scope sights within a close range of somewhere between 25 to 50 yards before zeroing to make the process easier and faster. Once you've done this, you're now ready to zero your rifle for your type of ammo. This is now called sighting in - the part of the zeroing process where you actually fire a bullet.
Sighting In at the Range
Now, you're ready for the gun range where you can set up on a shooting bench and set up your targets. This part of the process is about finding out your rifle's capabilities and to remove as much human-error as possible before you get onto the field.
If you bore sighted your rifle at 25 yards, start at 25 yards and then move backwards until you've worked your way to 100 yards. Many people find that starting at 100 yards straight-away will result in their bullet strikes being far off or not even hitting paper.
This reiterates the point that, if your scope has only been bore sighted, you are still not ready to hunt! You must sight in to zero your ammo to your rifle for a successful hunt.
While there are many ways to sight in and zero your scope, here are some basic instructions:
- Although your rifle will be supported for purposes of sighting in, it's still important to position yourself and hold your rifle as you would as if you were out in the field. Holding it differently when you're actually hunting will result in a different point of impact.
- If you have a variable magnification rifle scope, adjust it for the highest magnification that allows for the best, clearest, and sharpest image of the reticle possible.
- Load your rifle
- Align the reticle to the center of the bullseye/target
- Breathe slowly, close your eyes for 10 seconds and open. Make sure the reticle didn't float off your point of aim.
- Fire your first round.
- Examine your bullet strike and how far off it was from the center. Even if it was bore sighted for 25 yards, it may not have hit the center, but it should still be somewhere on there.
- Adjust the scope windage and elevation knobs for the appropriate amount of clicks until the cross hairs of the reticle are right on the bullet strike of the first shot.
- Now aim your rifle to now, again, be pointed to the bullseye.
- Fire your second round.
- You should now be hitting within the "10 ring" of a bullseye target. If not, repeat the process until you're close enough.
- Move back to 50 yards or 100 yards doing the same process.
You might also find the video below from Midway USA useful:
Troubleshooting Sighting In Problems
While sighting in your rifle scope, especially for the first time, you're probably more than likely to come across a few common problems that might frustrate you. Let's go over some rifle scope anatomy so that you can safely and effectively deal with them as they occur.
A hot barrel on a rifle can cause two things. The first is the steel tubes can warp, and second, the heat generated and rising off the barrel will cause a distorted view, making bullet strikes and groups seem higher than they actually are. All rifles with a light-weight barrel, doesn't matter what size caliber - again, for beginners, the caliber is the diameter width of the bore - the barrel will get especially hot during use and can affect your accuracy. It's important to remember it's not the rifle scope's fault. Just let the firearm take a break to cool off between shots in groups of three.
Using Different Ammo/Bullets
Not all ammo acts the same way. Even the same ammo made by different brands or different ammo but has the same weight will give a different bullet strike each time. When you sight in your scope, you'll want to use the right ammo for the distance. If you're going to be using a different type of ammo on hunting day, you'll want to zero it first to make sure you still get well-placed shots.
Using Different Distances
If you're hunting with longer distances than 100 yards, you'll need to make scope adjustments and sight in your ammo to compensate for bullet drop. For example, if you're sighted in for your type of bullet at 100 yards, you might want to shoot two or three inches higher than what you would at 100 yards to hit bullseye at 200 yards. There are also ballistic calculators available in other hunting optics such as laser rangefinders and rangefinder binoculars (like these) to do the math for you.
Air gun rifle scopes: Adjustment knob sensitivity
If you feel like you've sighted in, focused your reticles correctly, and you're still getting various bullet strikes, you might want to check your adjustment knobs to make sure your cross hairs are in line with where they need to be. Here's why...
The reticles are inside an erecter tube that is inside the scope tube. The erecter tube is being pushed and held in place by an adjustment knob and a spring. When the adjustments are too high and too far right, the compression in the spring relaxes and causes the erecter tube to move freely about in the scope tube. Your shot placements are going to be unpredictable and varied. Your adjustment knobs may also seem like they're not working, are mushy, or may even stop clicking all together. You'll want to reset your adjustments and start again, always making sure your clicks are always crisp.
Air gun rifle scope: Adjustment lag
When making adjustments to your scope, you might notice lag time where the adjustments don't really kick in until after you've shot off a few rounds. The vibrations from the shots is what places the erecter tube into position. Some air gunner users will tap or knock their rifle scope a few times to get it into place.
So there you have it. A simple run down of what it's going to take to get your scope mounted and sighted in. While the entire process may not be as easy as pie, it's designed to make sure your scope lasts, performs well, and that injury to yourself and others are eliminated.