How to Sight In An AR-15 – All You Need to Know

How To Sight In An AR 15
Alfred Mendoza

Shooters know the dauntless task of zeroing a rifle. In the case of the AR-15, it seems almost double the trouble.

There’s so much more to getting the perfect sight, so we came up with this quick 7-step to zeroing targets.

Here is how you can sight in an AR 15.

1. Gather the Tools Needed

It’s best to make sure you have everything you need from your rifle all the way down to your shooting mat with you. 

After laying out all the bits and bullets down, play around with your scope and make sure it’s installed properly.

A wonky, poorly installed scope is a recipe for missed targets, so as excited as you may be to start nailing exact fire, be sure to take as long as you need during installation.

Here are the tools:

  • Rifle
  • Ammunition
  • Screwdriver (slot head)
  • Target
  • Large target board
  • Staple gun
  • Sharpie
  • Hearing protection
  • Eye protection
  • Shooting bench or table
  • Tape measure
  • Sandbags
  • Gun rest

2. Implement Bore Sighting

Bore sighting is a technique that allows the user to get a rough idea of where a bullet would strike when fired with your rifle.

To effectively use this technique, you must rest firmly on the barrel and remove any obtrusions. 

It includes removing the gun frame or bolt, which prevents you from getting a clear view through the bore from the chamber to the end of the muzzle.

After completing these steps, you will then need to get your rifle “bore-sighted.” To achieve this, you must use your eye to center a distant object in the bore. 

Another, more precise but lengthy way of double-checking would be to separate your upper and lower receivers and remove the upper bolts to give you sighting room between the upper receiver to peer through the barrel.  

You will then need to make sure the bore and the center are aligned on both ends and then through the scope of your rifle.

3. Do Some Adjustments

In the event of your sights not aligning right away, here’s how you can do it.

Place a larger target, preferably a 3×3 piece of paper: the bigger, the better, exactly 25 yards from your position. 

The temptation to go farther downrange is high, but starting close will give you the most accurate adjustments. 

You can then try and “hit paper” on the first shot to clarify what adjustments to make.

When adjusting your rifle scope, it’s essential to adjust on both the windage and elevation sides to get a perfect balance. 


Although we’re all accustomed to making alterations based on audible clicks, this actually is not of great importance when making your first round of rough adjustments. 

Instead, focus on making sure the crosshair and the bore are both centered on the same object.

4. Find a Steady Rest

No matter the alterations made, accuracy will remain a tough challenge without a steady rest. 

With different physical builds and preferences, choosing a rest that works for you without trial can be confusing. 

When choosing and setting up a steady rest, always be sure to test it out by getting into your shooting position to see if it’s comfortable for your style.

Another factor to consider when choosing a rest for outdoor or free ranges is the surface type your rest will be resting on. We also recommend you check out the best barrel lengths for your AR-15

5. Shoot By Group

After making all the necessary alterations and resting your AR-15, carefully load it and fire a three-shot group. Group hits are better done with a pal to spot where your shots land. It’s easier to spot the point of impact.

If some, or in the worst case, all, of your hits, miss the paper, it’s best to make further alterations or redo the bore sighting on your rifle. Do another set of rounds.

It depends on how wide and how many of the shots missed of the rounds. If all three hit the paper, you’re all set for the next step!

6. Do Fine Adjustments

If all three shots hit the bullseye, you should be all set to find your optimal zero below. If it’s on paper but out of the center, you’ll need to adjust.

The most common and efficient way of doing this is by estimating the center of your three-shot group then marking it with a Sharpie.

Next, use a tape measure or, if you have it in handy, inch-stadia lines to find the horizontal and vertical distances on your group’s center to the bullseye. 

For instance, if it measures 2 inches right and 1.5 high of the bullseye, you will need to move the bullet’s POI that exact distance in the opposite direction. It means that you would be adjusting your rifle scope for 2 inches left and 1.5 inches down.

fine adjust

Once the alterations have been made, give your rifle scope a little tap. This little trick is known to help the alterations “settle” into the scope’s erector tube. You can then shoot test rounds. If all three hit the aim, then you’re set.

7. Find Your Optimal Zero

The AR-15 rifle, as with all rifles, can be zeroed for any scope of your choice. It’s essential to understand the optimal specifications for your intended use. 

For instance, your optimal zero for shooting a still target at 25 yards distance will most definitely have to be different from your optimal zero for shooting a moving object even at the same scope. 

If you are using iron sights, you need to find your mechanical zero on the sights to hit your target.

It is essential when shooting at long ranges. For example, most of us opt for zeroing at 100 to 200 yards away from the target. 

If your new rifle is zeroed in at 100 yards, your bullet will be dead on at exactly 100 yards, but high at 50 and low at 200 distance when you shoot. Zero your rifles at the furthest point your scope goes. 

For instance, a 100-yard zero is best and most practical for a 100-yard scope. Keeping your zero at the farthest point will keep it at 2-3 inches wide, making this the ideal setup for hunting, target, and defense shooting.

The best way to be sure of your zero of choice is to move the target to the range you’ve zeroed your refile to and repeat step 5. When your bullets hit precisely where you’d want at a given scope, your rifle is zeroed. 

Now every shot you fire will be a calculated shot!

Additional Expert Tips


Optic Options 

Choosing optics that work for you is very important. After all, it’s what you’ll be seeing your target through. 

There are flip-up sights offset from the shooter’s primary optic, usually at a 45-degree angle.

To pick the right one for you, it’s best to consider the purpose and conditions you’ll be using the new optic for, whether you’re using it for home defense or not.

Weather Conditions

As mentioned above, conditions can very well play a significant role in zeroing your rifle and any other rifle, for that matter. 

Rougher conditions may need some extra time and skill in zeroing. For instance, strong prevailing crosswinds may force you to make slight alterations to keep it optimal. (1)

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Range Time

Consider how much time you have at the range as you don’t want to spend your scheduled range time zeroing your rifle or guns. It takes practice though.

Moreover, there are bullet drop compensators that will allow us to compensate for bullet drop reasonably. You can find this useful in competition shooting as well.

Zeroing Routine

What kind of sight picture do you see when you’re using iron sights? Having a proper zeroing routine ensures you hit your target at the point of impact, it’s one of the shooting fundamentals.

You must understand the purpose of the front and rear sight when you do this. Keep in mind the position of the rear sight determines windage. 

Also, you need to adjust your front sight elevation and red dot sight by moving it to the left or right.

Whether you’re using a red dot, iron sights, or scope, alterations are needed for your point of aim, especially if you plan on joining shooting competitions. 

Practice a Hundred

Once you can nail zeroing at 100 yards with no issues, you’re sure to have a much easier time at any other scope.

If you practice regularly, red dot alterations, accuracy, and your overall zeroing routine for your aiming point become easy. For rough alterations, don’t think about counting clicks.

You can practice with your shooting community or join local long-range competitions so you can be confident in shooting in a straight line using red dots.

Parting Shots on Sighting In Your AR-15 Rifle

You have to keep in mind to adjust the front sight post until the base of the sight post is flush with the housing. 

It helps to practice in a shooting range regularly to become an experienced shooter.

Remember to adjust the front sight post until the base of the sight post is flush with the sight post housing. 

You have to make necessary adjustments by moving your windage to the left or right so that you can hit your target at a 100-yard zero.



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