Boresighting is a method of adjustment that aligns the optical sight on a gun barrel with the axis of the bore. Boresighting should always be given priority after you are done mounting the scope. This not only gives you a good reference point from which to start sighting in your gun but also saves you time as well as spending too much on ammunition or even from suffering some shoulder recoil.
It’s important, however, to remember that boresighting does not sight in your gun. You must do this by firing a specific type of ammunition from a distance.
The Origins of “Bore Sighting”
Boresighting is quite an old craft. There are several ways that boresighting can be done. The oldest method involves removing the bolt on a bolt action rifle and simply looking down the bore. The gun is secured so that it does not move, and is positioned to point at the bullseye of a specific target located about fifty yards away. The user then looks through the scope and carefully adjusts the windage turrets and the elevation until the reticle gets correctly centered on the bullseye, all the time being careful not to move the gun. Though this boresighting method has an elegance borne out of simplicity, its major drawback is that it cannot be used on many types of guns including lever guns, pumps, semi-autos and most types of handguns.
Collimators and Arbors
Using collimators and arbors is another old boresighting method. Arbors are also known as spuds. A collimator is a device that has a grid that resembles a graph paper that the user sees when looking through the scope. The collimator is held in place using arbors that are inserted into the barrel from the muzzle-end of the gun. The user looks through the scope and adjusts the windage and elevation turrets so that the crosshair is correctly centered on the grid. For this to work though, the spuds must be correctly sized. The big downside of using collimators and arbors is that some calibers such as .17 and shotgun gauges require their own specific arbor sizes which are often hard to get.
Using magnetic boresighters is one of the most convenient and effective ways to boresight. These boresighters simply attach the muzzle of your gun with strong magnets instead of inserting any arbors into the barrel. Some people fret about the idea of inserting anything into their barrels using a cleaning rod. The beauty of magnetic boresighters is that they fit all calibers and gauges, and no extra parts are required. Magnetic boresighters can be conveniently used to check zero after transporting your guns or after your gun suffers a hard drop or even after hard use. To accomplish this, sight in your gun to check where your crosshairs are located on the boresighter’s grid. Remember this placement (it’s best to write it down) and use it to check zero later.
Laser boresighters are some of the most popular boresighters around today. Some laser boresighters project a laser beam from an arbor that is inserted into the gun’s muzzle, while some have the dimensions of a cartridge case that the user can insert into the gun’s chamber and close the action. When using a laser boresighter, you need the target to be somewhat reflective so that it can reflect the laser beam. You should also use a gun vice to help you easily center the scope’s crosshairs into the laser point.
Points to Remember about Boresighters
- No boresighter can sight in a gun. Boresighting can only be done by shooting a gun using a specific type of ammo from a distance. Different ammos have different impact points.
- Always remember to remove your boresight arbor before shooting
- Every shooter should aim to own a boresighter whether they mount their own scopes or not
The Best Boresighters
Boresighters, just like any other gun accessories, are not created equal–some are great while others are more average. Here is an overview of some top boresighters:
1. SiteLite Ultra Mag Laser Professional Boresighter
SiteLite Ultra Mag Laser, also known as SL-150, is a laser boresighter that uses a red laser with a battery that can give 40 hours of continuous service. The boresighter sells for $149.95 at Amazon where users have given it a perfect 5-star score. This boresighter weighs 1 pound and is popularly used by the USMC and US Navy weapons that range from 5.56mm to 20mm canon. The SL-150 includes the Ballistic Targeting System software program that can be used to create a custom laser boresighting target for a specific rifle and ammo type. The boresighter comes with a lifetime warranty and an optional app for use on an iPhone or iPad.
2. Wheeler Laser Bore Sighter
The Wheeler Laser Boresighter is a professional boresighter that uses a high-power visible green laser that is easily visible even in bright daylight. The boresighter weighs 1 pound and uses a high-strength magnetic connection to the barrel that delivers fast and accurate bore sighting. The magnetic connection helps to precisely align the bore without risking damaging the gun’s bore. The borseighter has a well-machines aluminum body with a soft rubber over-molding that houses the laser module.
3. Bushnell Magnetic Boresighter
The Bushnell Magnetic Boresighter is a low-budget boresighter. The boresighter is also light-weight as well, weighing just 4.8 ounces (0.3 pounds). This Boresighter sticks to the end of a gun barrel by means of its powerful magnet that is located below the bell of the boresighter. The boresighter can be used effectively on rifle barrels of .22 caliber all the way to .50 caliber, as well as stainless steel barrels. It also works well on shotguns and handguns. The manufacturer says that it can be used with red dot optical sights, adjustable iron sights or telescopic sights.
4. Sightmark .22LR Boresight
The Sightmark .22lr Boresight is another low-budget but effective boresighter. The boresighter weighs just 4.2 ounces (0.26 pounds) and can be used without firing shot—simply chamber the bore sight just like you would a regular bullet. A laser dot will appear where the rifle is aiming. Live fire can be used to fine-tune the gun to compensate for inconsistencies such as when the gun is fired at a distance.
Boresighters are generally quite affordable and you should aim to have your own. With so many varieties available, buying a good one might simply boil down to whether you are comfortable with the working mechanism of a laser boresighter or those of a magnetic one.