How to Sight In and Zero an AR15 at the Range (When You Don't Have 100 Yards to Use)

Zeroing an AR 15
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How to Sight In and Zero an AR15 at the Range (When You Don't Have 100 Yards to Use)

One of the great things about the AR platform is that it's so versatile. You can use it for targets that are close as well as those far away.

But to hit what you're aiming at, you have to first zero or "sight in" your rifle.

So, how exactly are you supposed to do that so you can shoot things at 100 yards when you don't have 100 yards to shoot in for practice?

Thankfully, based on the way this rifle shoots, it's actually easy to do.

What Is Sighting?

Sighting is the practice of adjusting your sights so that the bullet makes its impact at the exact spot where you're aiming.

In the military, this is referred to as zeroing. Sounds pretty straightforward, right? It is.

Unfortunately, some people get overwhelmed by this process. It's understandable if you've never done it before that you might be a little intimidated.

But don't worry — keep reading, and you'll have your AR sighted in no time.

Why Should I Sight My Gun?

When you purchase the rifle, the sights may or may not be properly adjusted to how you hold the rifle and look down the sights.

This may be true regardless whether you're using the traditional iron sights or you've got an optic mounted on your rifle.

The reason for this is that every person is different. Each person is going to hold their rifle differently, and each person's vision is unique.

The way someone looks down the sights while holding a firearm is also usually unique in some way.

This is why you need to zero the rifle: In doing so, you adjust the rifle to you.

Sighting is going to vary based on how you hold and fire the weapon, so just because your rifle is "zeroed," that doesn't mean it's  ready to go.

Your rifle should be sighted to you, not the gun itself; just because you can hit the target with your sighted rifle doesn't mean your friends can (and vice versa).

How to Sight

Sighting isn't an overly complicated process. Typically, it involves finding a target, aiming at it and shooting a series of shots.

The number of shots you take can vary; typically it's two or three.

The military standard is three, so that's what we'll go with for the purposes of this discussion — if it works for them, it'll surely work for us.

Once you've fired your three rounds, look to see how close this group was to where you were aiming.

Then, go back and adjust the windage and elevation on your sights and repeat the three shots. Look at how close these were, and repeat the process until you hit the spot you are aiming at.

Bear in mind that the sights might have been placed on the rifle very differently from how you would be looking through them, so don't get frustrated if it takes awhile to get on target.

It takes as long as it takes; there's no need to rush.

If it takes you all day just to get a gun zeroed, so be it. What you don't want to do is hurry through it.

Take your time, and you can feel confident you can hit where you aim.

Points to Consider When Sighting

First, ensure your aim is consistent. For this process to work, you must have the exact same sight picture every single time.

Sometimes, aiming at the center of a target can be a bit subjective, so try to pick something on your target that absolutely is not moving and consistently shoot for that.

If that isn't the center of the target, that's fine. Once you're consistently hitting that point, move it over to the center of the target and give it a whirl. You should now be hitting dead on.

It's also extremely important that you don't try to adjust after only one shot.

One of the main reasons that the military likes using three shots is because it's very easy to have one shot inadvertently go off target from where you're aiming.

This could be due to a number of factors, including how you pull the trigger. You could have adjusted your support arm unknowingly; or, maybe you even sneezed.

Regardless of why it happens, it isn't uncommon to find one round veering off from where you were intending.

But if you shoot a series of three shots at a time, even if that happens, you'll have an idea of where you're aiming because the other two will still be grouped together.

Sighting for Specific Distances

Now that we have the basics for the process of sighting your rifle down, we can move on to sighting for a specific distance.

Before we get into that though, we need to take a moment to understand why we're able to do this.

The reason that we can (and need to) zero-in the rifle to a specific distance is because of the trajectory of the round — or the way the bullet flies.

Understanding Trajectory

When a round is fired out of your AR, it doesn't actually move in a straight line. As it first leaves the barrel, it drops down slightly.

Then, as it moves forward, it comes up in an arc and eventually finds its way back to the point where you were aiming.

Because of the spin placed onto the round as it travels through the barrel to the rifling, it moves in an arc similar to a football when you throw it.

The drop happens when the round first exits the barrel because it's coming into free space for the first time.

Basically, this is gravity taking hold of it. But, thanks to the tight spiral placed on the round, it starts to go up again very quickly.

This arc of the bullet as it flies through the air is its trajectory.

An interesting phenomenon results from this where the round will cross your line of sight twice along its journey — once at the beginning and once at the end.

This happens regardless of whether you're shooting 5.56 or .223, and this is how you're able to sight in the rifle for 100 yards without having 100 yards to shoot in.

An Important Caveat

Even though the trajectory of the round does put it at roughly the same place twice along its journey, it isn't exactly the same.

Yes, you can zero at the first point of the flight path, which is the smaller range, and hit in the general vicinity on the longer range.

In fact, that's how the military does it for general infantry.

However, it will be slightly off. This isn't going to be enough to make you miss drastically, but it will be slightly different than exactly where you were aiming, so keep that in mind.

The 100-Yard Zero

The most common range length to zero for 100 yards is 25 yards.

Most people have access to a range with at least one 25-yard length, so that's what we will use. If you do have access to more, this process can be done on greater distances.

Even if you don't have an area that quite goes out to 100 yards, you just need to know what the trajectory of your round is and take it from there.

You can find that from your ammo manufacturer.

When sighting in for 100 yards at 25 yards, you want the round to impact slightly below where you're aiming.

You can find targets that are specifically designed to give you the place to aim and the place for impact. If you don't have those readily available, just know that it's going to be about an inch and a half below where you're aiming.

If you're consistently placing your group at an inch and a half below the bullseye at 25 yards, you should be hitting bullseyes at 100 yards.

All in all, this process is actually pretty straightforward and quite enjoyable.

Don't worry about all of the what-ifs and other things that can go into trying to zero for a longer distance on a shorter range: even if it isn't exactly dead on when you go to a longer range, you'll still be hitting on the target.

Getting it dialed in to precision after that won't be an issue.

Getting your rifle sighted is something that you really ought to do; but just because you have to do it doesn't mean it needs to be a chore.

Regardless of how much room you have to sight, you can end up with the zero you want. Just follow the steps we've outlined here and enjoy the process.

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Probably ought to bring up the size of the adjustments. A shooter needs to know what the unit of adjustment increment that they have on their rifle. One minute of angle (MOA) is fairly standard, but many rifles have more precise adjustments such as 1/2 or 1/4 MOA. One unit of adjustment is also called a "click" because the sight makes a tiny click noise when it is adjusted. One minute of angle (MOA) equals about 1 inch of adjustment of the point of impact per unit of adjustment change on the sight AT 100yds, 2 inches at 200yds, 3 inches at 300yds and so on. So you can see that a single 1 MOA adjustment at the rifle end can have very big differences in point of impact changes downrange. Because of this, using one MOA sights at 25yds yds and making only a one unit of adjustment change(click) gives you only 1/4 inch in the change of point of impact of the bullet. If the group is one inch lower than you want it at 25 yards you will need to use 4 units or clicks (up) of adjustment to move the group one inch higher where you want it to go. If you are using the more precise 1/4 MOA sights you would need 16 units of adjustment to get the same one inch movement of the point of impact for the bullet to be higher by one inch. When you are satisfied with your results at 25 yards enjoy the practice. and touch up your zero when you get a chance to shoot at 100 yards.
Good advice.