How to Boresight a Rifle: A Beginner's Guide to Fast, Accurate Zeroing

When you purchase a new optic for your rifle, that optic is not going to be accurate right out of the box. Before depending on your optic to help you hit exactly where you mean, you’ll have to zero it. Sighting in your scope can take a long time and waste a lot of ammo. Fortunately, there is a solution.

There is a more efficient and faster way of zeroing in a new optic. By using a laser boresight, you save time and money by making sighting-in much faster without using any ammo!

What Is Boresighting?

Bore sighting is a reliable way to align your reticle, sights and scope’s crosshairs with the true center of the gun’s barrel—which is the bore. Boresights use a laser diode to project a dot on a target much like a laser pointer, making it easy to see when your crosshairs align with the laser. Since the two run parallel to each other, they can only truly zero at a given distance. This is typically 25 yards.

You can bore sight any firearm—AR-15 and other MSWs, shotgun, bolt-action, and handguns. Bore sighting also works on any sighting system—red dot, reflex, riflescopes, holograph and even your iron or night sights.

Types of Laser Boresights

There are two different types of laser boresights—one you put directly into the chamber and one you insert into or attach to the barrel.

In-Chamber Boresights

In-chamber boresights are inserted directly into your gun’s chamber, so they must be caliber-specific and made to the same dimensions and specs as a cartridge in that caliber. These types of boresights are the most accurate. These can, however, become costly if you have firearms in multiple calibers that you need to sight in, because you must purchase a separate boresight for each caliber.

Laser boresight cartridges are easy to use. You simply turn them on and insert it into the chamber of your firearm like you would a live round or snap cap.

Sightmark in-chamber boresights are superior to competitors, due to the multiple set screws that lock in the laser diode, ensuring the laser stays straight and centered. To test an in-chamber boresight’s accuracy, roll your laser boresight on a flat surface—the laser should stay straight along the wall as you roll it. If the dot rotates, the diode is canted and cannot be trusted for precision alignment.

Made of high-quality brass, the Sightmark boresights are calibrated to make sure the laser is true to center, and measure precisely the same specs as a live round. The extensive offerings include 12- and 20-gauge shotgun, popular self-defense handgun calibers, and over 30 different rifle calibers—including .223/5.56, .308, .50, .300 BLK, and 6.5 Creedmoor.

How to Use an In-Chamber Boresight

1. Use a benchrest, shooting bags, or another stable platform. Make sure the firearm is unloaded and pointed in a safe direction.
2. Hang a target 15 to 25 yards out.
3. Insert the batteries into the boresight. It should activate once assembled.
4. Lock the bolt open and insert the boresight into the chamber.
5. Line the laser dot onto the center of the target.
6. Look through your optic and adjust the windage and elevation knobs until your reticle aligns with the laser.

Universal Boresights

Universal boresights either insert into or attach to the barrel. Most inserted types come with arbors to fit different barrel sizes. These are more affordable but can have drawbacks:

• Arbors can be lost, worn out, or break.
• The boresight may not seat consistently in the barrel, reducing accuracy.
• Safety concerns: forgetting to remove one before firing can destroy your barrel.

Sightmark’s universal boresights solve many of these issues by using a strong magnet to stay on the muzzle and a minimal arbor for alignment. No arbors to lose, no small parts to break. They’re compatible with .17 to .50 caliber barrels.

How to Use the Universal Boresight or Boresight Pro

1. Stabilize your firearm and ensure it is unloaded and safe.
2. Set a target 15 to 25 yards downrange.
3. Turn on the boresight (the Pro model activates when pressed onto the barrel).
4. Remove any muzzle device before attaching the unit to the barrel.
5. Attach the boresight magnetically to the muzzle.
6. Look through your optic and align the reticle to the laser dot.

Final Steps: You're Ready for the Range

It’s as easy as that!

Now, you are ready to head to the range to fine-tune your zero. It shouldn’t take but a few rounds to dial in your optic precisely. Boresighting gets you on paper quickly and saves ammo in the process.

Remember to boresight your firearm anytime you install a new optic, upgrade factory sights, before hunting season, for competitions, or after long-term storage.

Click here to shop boresights at Sightmark.

Do you have questions about boresights? Leave them below and we will do our best to answer them.