AR-15 Bore Sighting: How to Laser Bore Sight an AR15

If you didn’t know before, bore sighting your AR-15 is the fastest way to get on paper. It saves time, saves money, and saves ammo. 

But how do you bore sight an AR-15? Read on to find out everything you need to know for AR-15 bore sighting.

What Is Bore Sighting?

Bore sighting with a laser means using a laser to illuminate a dot on the target in front of you. The laser bore sighter either sticks out of the muzzle end of your gun, be that a rifle or a pistol, or it’s a laser installed into a caliber correct housing that looks like a spent brass shell. 

The muzzle lasers stay on until you turn them off. But breech lasers stay on for a few minutes, then automatically turn off.

Here is the bore sighting process:

With the laser securely in the barrel, look through the sights. Adjust as needed to get the sight centered on the dot, which is usually red but can be green.

Unless you get lucky, you won’t be precisely on target with a bore sight, so you’ll need to make fine-tuning adjustments through the sight. 

On many AR-15 iron sights, you can adjust the rear sight for elevation and windage. The front sight usually adjusts only for elevation. Optics, however, have controls for both adjustments in the same area of the device; the elevation turret is on the top, and the windage is on the side.

Bore sighting means you are aligning the barrel with the target downrange. At distances of 100 yards or more, this means your windage should be very close to spot on. However, elevation will be off.

No matter how fast a bullet moves, it drops over distance. The farther out the bullet gets, the more it drops. The good thing is that online ballistic calculators can do the math for you if you need to know bullet drop over a set distance for a certain bullet weight and caliber.

A laser beam does not drop over any distance. This means if you use the laser to sight in dead on at 100 yards, your bullet will hit below that mark. How much below varies widely by caliber.

What’s a Laser Bore Sight?

A laser bore sight is a low-power laser that can come in two forms: mounted in a caliber-specific housing or at the end of a stick that has an adjustable stem. Sightmark makes a wide variety of caliber-specific laser bore sights, and LaserLyte’s multi-caliber bore sighter has the stem with adjustable end pieces. (1)

Which Is Better?

Given a choice between the multi-caliber and caliber specific, you’re probably wondering which is best. That depends on you, your gun (or guns), and how often you need to sight something in. (2)

Multi Caliber

If you have several to many guns and you regularly tinker with the sights, then a multi-caliber bore sighter is a better idea. You can swap the plastic bore guide that fits into the stem, called an arbor, on the end in a few seconds. You can easily move from a .17 all the way to the .50 with the same device.

The drawback is you have a lot of small parts to keep up with. The screw in the stem is the smallest part and is very easy to lose.

Caliber Specific

If you shoot the same gun or the same caliber in different guns and also change the scope or adjust the sights frequently, then a caliber-specific device is better. Since you have one item, and it’s the size of your ammo, it’s easier to keep up with.

The drawback is you must have a different device for different calibers. While a .308 Winchester bore sighter will chamber in a .30-06 Springfield, the reverse is not true.

Also, the .308 Win, being a shorter cartridge, will not fit into the chamber of the ‘06 as precisely as the ‘06 bore sighter. A .223 bore sighter will not fit at all into a .45-70 chamber and vice versa.

How to Bore Sight an AR-15 Inside or Outside

You can bore sight an AR inside or outside since you are not actually pulling a trigger on a live round. You are just adjusting sights. The bore sighting process is fairly simple. A shooting rest makes this easier.

Here is how to bore sight an AR-15 in 6 easy steps:

1. Mount your target. 100 yards is a common distance. If you are doing it inside, you may have to use a shorter distance. 
2. Position the gun in a brace or holder. It can be as fancy as a lead sled, more moderate like a gunsmith rack, or even just laid across something that will hold it in place. I have folded a jacket and put it on the hood of my truck for a rifle rest. 
3. Turn the bore sight on. If you are using a muzzle device, look for the on-off switch. If you have a cartridge style, you have to chamber it. Sometimes closing the bolt turns the laser on. Sometimes you have to squeeze the trigger. The firing pin strikes the switch where a primer is placed. 
4. Look through the sights for a laser dot on the target. 
5. Adjust the sights so they are “on” the laser dot. This is the part where having a brace to hold the gun steady is very important.
6. Remove the bore sight.

Here’s a video featuring the noted hunter Keith Warren who talks about laser bore sights and how to use them:

The same process is used for an AR-15, a bolt action rifle, pump, single shot, and other semi-auto rifles, shotguns, and handguns. (3)

If you use laser bore sighters with an adjustable insert on the arbor, choose the appropriate plug and expand it just enough to lightly grip the barrel when you push it in. Then, gently twist the device to get a firmer grip inside the barrel and push it until the laser head is flush against the barrel crown. Very lightly tighten it again.

This makes sure the device is centered in the barrel.

At the range, shoot your gun using the newly adjusted sights. This will show you how much fine-tuning you need to do. You can use the same target for both sighting in methods.

Alternatives to a Laser Bore Sighter

Here’s the thing: you do not need laser bore sighters to get on paper. The Bushnell Banner Boresighter is an example of an alternative method. 

This device uses an arbor and stem to go inside the barrel, while the sighting device sits on top of the barrel. You look through your scope and the sighter at the same time and make the rough adjustments to get on paper.

The advantage here is these sighters do not need batteries. You can pack up the sighter and not worry about batteries going bad or leaking acid into the battery case to ruin the device.

That said, a disadvantage is the height over the bore. If you have raised sights – as many AR-15s do – then you won’t be able to see through the device properly.

The Big Mistake

The one big mistake people make when using any kind of bore sighting device is they believe their gun is properly sighted in after. It is not.

Bore sighting devices get you close. At 100 yards, you may be as much as 4 inches off center using the Bushnell Banner mentioned above, and that is based on a straight line from the barrel. With a laser, you can get a bit closer – if the laser is properly centered – but you must still figure in bullet drop.

In a round like the .223 or 5.56, bullet drop over 100 yards is slight. If you move into bigger rounds like the .450 Bushmaster on an AR-15 platform, bullet drop is much greater. 

At distances of 100 yards or less and shooting at deer-sized animals or larger, this is not a huge concern. A deer’s vital section is 6-7 inches. Bigger animals have bigger breadbaskets, in turn.

If you’re shooting varmints, the difference of an inch is big enough for a humane kill or a clean miss. A prairie dog is a small enough target at close range. So, if you are bore sighted at 100 yards and you’re aiming at a p-dog at 250 yards, you will miss.

You must hit the range and throw some lead downrange to fine-tune the sights, be they iron or optic. You also must sight in each upper receiver as it has the barrel, and each one has a different point of impact.

CAUTION!

Never shine the laser into someone’s eye. You can blind them because the laser can permanently damage the retina.

My Results

I use a muzzle-mounted device with an adjustable plug and arbor. I shoot rifles ranging from .22 short up to the long-range behemoth .50 BMG.

When I go to the range, I typically have several guns to shoot. Being a professional gun journalist, I am also taking a variety of sights to shoot on several guns.

Multi-caliber bore sights work best for me because I have all I need in one small pack in my range case.

More Reading

Best AR-15 Optics

For more reading, our article on the best AR-15 scopes money can buy is a good next step. We go over what are the perfect AR scopes.

Removing the Front Sight on an AR-15

If you’re interested in swapping out your iron sights, take a look at our write up on how to remove the front sight on an AR-15 rifle.

FAQ

What does bore sighting mean?

Bore sighting means using a device to make rough adjustments to your sights, iron, or optic. You still need to make fine adjustments to achieve maximum accuracy.

Can you bore sight at 25 yards?

Yes, you can bore sight at 25 yards. This is a good distance to start with a pistol version AR-15. You still need to make sight adjustments for your expected shooting distance. Know that bore sighted does not mean zeroed.

How accurate is a boresight?

Boresighting accuracy is around 4 minutes of angle at 100 yards. A minute of angle (MOA) is an inch at 100 yards. The real question is: is laser bore sighting good enough?

Well, it’s good enough to get your bullet on paper at 100 yards. However, it’s not good enough for hunting or precision shooting.

How far is a bore sight good for?

A bore sight is good for 100 yards or less. The farther out you go, the greater the elevation error will be. 

Can you bore sight at 100 yards?

You can bore sight at 100 yards. This is a recommended distance for bore sighting an AR-15. The laser dot will be 2-4 MOA at 100 yards.

How far off is a bore sight?

How far off a bore sight is depends on how far away you are from the target. In general, expect to be off at least 4 inches at 100 yards. That is good enough to get the bullet on paper. 

What bore sight does the military use?

The military does use bore sights, but each branch has its own devices. A common one is the Site Lite.

What is the difference between bore sighting and zeroing?

The difference between bore sighting and zeroing is that the former means adjusting the sights to be roughly on target, while the latter means making fine adjustments. 

With bore sighting, at 100 yards, you could be several inches away from dead center. Zeroing, conversely, means you adjust the sights to be dead center at the given distance at which you’re sighting in the rifle.

Does Cabelas bore sight rifles?

Yes, someone in the gun department of Cabelas will bore sight rifles for you, especially if you buy the gun there. If you bring in a gun, that’s up to the store. If you buy the gun or rifle scope there, the bore sighting should be free. And if you bring in your setup, the store may charge you a small fee.

Does bore sighting work?

Yes, bore sighting works – when you understand its limits. Bore sighting gets you on paper, so you burn less ammo getting centered.

Can you laser bore sight iron sights?

Yes, you can laser bore sight iron sights, red dots, laser sights, thermal scopes, and night vision scopes.

References

1. FDA, Laser Products and Instruments. Retrieved from https://www.fda.gov/radiation-emitting-products/home-business-and-entertainment-products/laser-products-and-instruments
2. Steven L, How to Choose a Bore Sight. Retrieved from https://www.opticsplanet.com/howto/how-to-choose-and-use-a-boresight.html
3. Reed Richardson, American Rifle: A Biography of the AR-15. Retrieved from https://talkingpointsmemo.com/longform/american-rifle-ar-15-biography