How to Sight In A Rifle Scope [2021]: Zeroing Made Easy

by Ryan Cleckner

January 6, 2021

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After you’ve mounted a scope onto a rifle, you’ll need to go to the range to sight it in (sometimes called “zeroing”).

There are plenty of techniques to sighting in a riflescope – some are great, and some are a waste of time and money. As a sniper instructor, I’ve helped hundreds (thousands?) of shooters zero their rifle scopes and I’ve seen them all.

In this article on how to sight in a rifle scope we’re going to explore the best techniques and tricks I’ve used over the years.

We’re going to cover:

What is “Zeroing” or “Sighting In” a rifle?

Zeroing your scope to your rifle, or “sighting in your rifle,” is the first step to being able to hit where you’re aiming.

Sighting in a scope involves moving the scope’s reticle (what you use to aim – usually “crosshairs”) so that your point of aim (where you aim on the target), is the same as your point of impact (where your bullet hits the target) at a certain baseline distance.

That might sound complicated, but the process for zeroing a rifle is actually quite simple.

By properly adjusting your scope you’ll be able to set it up so that where you’re aiming, is where you’re hitting, at a certain distance. Once everything is set up properly, your rifle will then be “zeroed” or “sighted in” for that distance.

If you’d like to shoot farther or closer than your “zero distance” then you can either “hold over” by aiming higher, or you can adjust your scope’s reticle to compensate for the bullet’s drop at the new distance.

Before we get into the adjustments you’ll need to make on your scope, let’s explore what the right distance is for your particular rifle and scope.

Scope Adjustments

BEFORE you go to the range to zero your rifle, please do the following:

  • ensure the scope is mounted on the rifle to fit you,
  • focus the ocular focus setting to your eye,
  • take the time to familiarize yourself with your scope and the adjustments necessary to zero the scope to your rifle, and
  • double check that your scope is properly secured to your rifle (I’ve made this mistake before)

For each of the items on the checklist above, and for actually sighting in your rifle scope, you’re going to need to be familiar with different scope adjustments. For a more in-depth discussion on your scope’s adjustments, check out How to Adjust Your Rifle Scope.

For help mounting your scope so that it fits you and your rifle, check out this video I did with the NSSF about 10 years ago (pre-beard):

At the 11:00 minute mark in the above video, I discuss focusing the ocular focus. THIS IS IMPORTANT and the most common mistake I see with shooters and the scope on their rifle. Only with a crisp and clear reticle can you effectively use your scope.

Once your ocular focus is properly adjusted, consult with your scope’s owners manual or examine the scope to determine what tools you might need to make adjustments while sighting it in.

While at the range zeroing your rifle, the only adjustments you should expect to be making to the scope are elevation and windage adjustments.

Elevation Adjustments: The turret on the top of your scope will adjust the impact of the bullet on the target up or down. This is called “elevation.”  The elevation turret (the knob you adjust) will be marked with a direction arrow – this arrow refers to the bullet’s impact and NOT the direction the reticle moves. If you want the impact of the bullet to go up the target, you turn the turret “up.” If you look in the scope while you’re making this upward adjustment, you should notice the reticle moving down.

Wait, what?

That’s right. Moving the bullet impact on the target up requires the reticle moving down. Think about it this way, the direction of the barrel determines the impact of the bullet. If the reticle is moved down, then you will need to point the rifle higher (move the barrel up) in order to put the reticle back to the point at which you’re aiming.

Windage Adjustments: The knob on the right side of your scope (99% of them) is the windage turret and it adjusts the impact of your bullet left or right. Make a note now of which direction is which, because this is easy to forget. In my book, The Long Range Shooting Handbook, I teach a mnemonic to help you remember how most American scopes adjust: Imagine you’re at a party and you run out of beer. You are going to go get more, but you don’t want to be left out on the fun, so you’ll be right back.

This mnemonic works this way: Left, out. Right, back.  Moving the bullet left, means turning the windage knob “out” or away from you, whereas moving the bullet right requires moving the knob “back” or towards you. Again, this is most American scopes…. not all scopes.

Units of Adjustment: Your scope will adjust in units of adjustment that you must be familiar with (either Minutes of Angle (“MOA”) or Milliradians “Mils”). Again, if you’d like to dig deeper I refer you to my book, The Long Range Shooting Handbook.  If you’re dealing with MOA, here’s an article that might help: Understanding Minutes of Angle. If you’re dealing with Mils, here’s another video I did: Understanding Mils

The point is this: you need to understand how your scope adjusts before you start the next section…

Steps to Sighting in Your Rifle

For me, the steps to the most effective and efficient way to sight in a rifle scope include:

  1. Bore-sighting
  2. 25-Yard Zero
  3. 100/200 Yard Zero
  4. Slipping Scales (zeroing)

I run through each of these steps to sighting in your rifle in this video here:

Bore-sighting: Bore-sighting is an extremely crude, yet effective, method to start sighting in your rifle. With practice, you can get quite close to an actual zero with this method – if I take my time, I can get within a couple of inches at 100 yards by bore-sighting alone.

Bore-sighting involves looking down your rifle’s barrel (the “bore”) and aligning the scope’s reticle to wherever the barrel is point at 100 yards.

For the best results from bore-sighting, take extra care to ensure that your rifle is well supported and completely stable. Then, after removing your bolt, look down your barrel at something that is easy to see/identify at 100 yards. If you’re using an AR-15 style rifle, you can still do this by removing the rear takedown pin and pivoting the upper receiver so that you can see down the barrel, with the bolt carrier group removed.

Next, move your eye up to the scope without moving the rifle and adjust the reticle until it aligns with what you see through the barrel. It will likely take you a few times of moving your head from the barrel to the scope, to get this right.

25-yard zero: If you’re really confident, or short on time, you can skip this step but I don’t recommend it. In fact, if you’re short on ammo, it is MUCH better to include this step. It spends one more round of ammo now, but it’ll likely save you many more later.

A 25-yard zero is as simple as this: shoot at a target 25 yards away and make an adjustment so that your impact would have been about an inch lower. I write ‘about” because we’re not going for a perfect zero here – instead, we’re just ensuring that your bullet at a further distance, will be on paper.

By skipping the 25 yard zero, you might waste rounds at 100 or 200 yards (whichever distance you choose) if they don’t impact the paper, and therefore you don’t know which way to adjust.

Regardless if you’re dealing with a Minute of Angle scope, or a Milliradian scope, please remember that your adjustments for 25 yards will be four times as much as they will be at 100 yards. For example, moving 1 inch at 100 yards would be about 1 MOA. However, moving 1 inch at 25 yards is 4 MOA. This is because 1 MOA is about 1″ per 100 yards, and is therefore only 1/4″ at 25 yards.

I’d love to get into this more now, but if you’re not confident on these measurements then check out my other videos, articles, or book.

Once you’ve shot one round and made the appropriate adjustment to be about 1-inch lower at 25 yards, it is your decision if you’d like to shoot again to confirm, or move out to a further distance.

100/200 Yard Zero: The 100 or 200 yard (or meter, of course) zero is going to be your final/actual zero to sight in your scope to your rifle. I choose 100 yards for my rifles but there are cases where a 200 yard zero can make sense. Please see the discussion below about choosing your zero distance for help making this decision.

When you’re ready to zero your rifle at the final distance, you should ONLY shoot groups of bullets. A single bullet is fine at 25 yards if you’re confident in your shot (you didn’t make a bad shot), but for getting a solid baseline setting for your rifle and scope you must shoot at LEAST 3-round groups.

After you’ve taken your time and made at least the best 3 shots you can make at your 100-yard target, determine the center of your group, and make the appropriate adjustment to wherever you were aiming.

If using an MOA scope at 100 yards, you’ll determine how many inches the center of the group needs to move (up/down and left/right) and then make the appropriate adjustments on your scope. If a 1/4 Moa per click scope, you’ll need to adjust 4 “clicks” per MOA.

If you’re using a Mil scope, you’ll need to determine the number of centimeters to adjust your group and then adjust that many tenths of a Mil on your scope for the appropriate direction.

Once an adjustment has been made, shoot another group to confirm. If you’re all set, you can move on to the next step. However, if you need to adjust again, make the adjustment and shoot another group to confirm as needed until the center of your group is aligned with where you are aiming.

To make this process easier, we made targets with a grid reference to help you know how much to adjust for each distance. On our rifle zero targets, we included the adjustments needed on your scope for a certain spot on the target, depending on how far away you are when you shot it.

Slipping Scales (Zeroing): The final step, after your scope has been adjusted to where your point of aim is the same as your point of impact at the zero distance you choose, the next step is to “slip your scales”, or zero your scope, if that adjustment is available on your scope.

This step involves moving the turret so that the “0” on the turret, aligns with the indicator mark on your scope so that if you make an adjustment in the future, it is easy to get back to your zero.

On most scopes, this involves loosening three hex-head screws on the outside of the turret, turning the turret until the “0” is aligned with the reference mark, and then retightening. It is VERY important to ensure that the actual adjustment in the scope (the “clicks”) is not moved as you turn the cap – the turret should freely spin.

Once set and tightened, the reticle and turrets on your scope will be zeroed to your rifle.

Things to Avoid when Sighting in a Rifle

Just as there’s a right way to sight in a rifle scope, there’s also a wrong way to zero your rifle.

Of course, this is my opinion, but… isn’t that why you’re reading this article?

Laser Bore-Sighting: In my unvarnished opinion, laser bore sighters are junk. Don’t waste your money or your time.

I’ve seen countless examples of shooters trying to use these and I’ve never seen them work. Want to zero your rifle scope the right way? Watch the video and read the description above.

Starting at 100 yards: Yes, I’ll be a hypocrite here. You should not start at 100 yards even though I have. Starting at 25 yards saves time, ammo, and frustration when you can’t even tell where your bullets are impacting at 100 or 200 yards.

Making Adjustments after 1 Shot at Distance: If you decide to shoot one shot at 100 or 200 yards and then make an adjustment, you’re going to waste time and ammo. SHOOT A GROUP before you adjust at distance.

If you shoot one shot then adjust, another shot then adjust, you’re going to be “chasing” your bullet impacts all over the target and get frustrated.

Instead, even if you see you first shot is not where you were aiming, shoot at least two more to get a good sampling before making an adjustment.

Failing to “Slip Scales”: I get it… it might be a pain to slip your caps so that “0” is lined up when your scope is zeroed. But trust me, two years from now you’ll be thankful you did because you won’t be wondering where you scope is adjusted.

What is the Right Distance for Zeroing Your Scope?

The best distance for zeroing your rifle will depend on your intended purpose for the rifle.

As a general rule, if you’re using a rifle for target shooting, it is best to zero it at 100 yards (or 100 meters) and if the rifle is strictly for hunting, then it is best to zero it at 200 yards (or 200 meters).

Why the different distance for zeroing rifle scopes? Great question…

For target shooting with centerfire rifles, I use a 100 yard zero (for rimfire rifles, a closer zero like 25 yards is likely more realistic). In my opinion, the 100 yard zero is best because you’ll only adjust the impact of the bullet up from your 100 yard zero for most every centerfire caliber – this is true for distances further AND closer than your 100 yard zero.

Yep, you read that right, with a 100 yard zero on your rifle, you’ll need to adjust up (or aim higher) to hit where you’re aiming at 25 yards. This might sound counterintuitive, but think about it this way: if you were trying to hit a spot on a target 1″ in front of your muzzle, would your scope need to be aimed at the spot you’re trying to hit? Or a couple inches higher? That’s right, it’d need to be aimed higher because the scope is mounted above the barrel.

At 25 yards, with a 100 yard zero, your bullet should impact about an inch low. Sure, you can argue with me in the comments, or you can go try it yourself and see. 

When shooting further than 100 yards, your bullet will keep falling due to gravity and you’ll need to adjust more and more elevation, the further out you’re shooting.

So, if the 100 yard zero ensures that you’ll never “dial” your scope down, then why would a 200 yard zero be good for hunting?

A 200 yard zero is often good for hunting because many hunting situations, and most hunting scopes, aren’t great for “dialing” elevation. With a 200 yard zero, you’ll be a couple inches high at 100 yards, and a couple inches low at 250 yards (for most calibers). This means that you can just aim in the kill zone of an animal out to around 250 yards and regardless of the distance, you’ll have a good hit.

So, it’s up to you which distance you want to zero your rifle and scope but know this: I zero ALL of my scopes at 100 yards so I don’t forget.

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About Ryan Cleckner

Ryan is a former special operations sniper (1/75 Ranger) and current firearms attorney, firearms industry executive, university lecturer, and bestselling author of the Long Range Shooting Handbook.

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