What Is Boresight?

A boresight is an implement to align a newly mounted scope with the barrel of a firearm. The boresight attaches in some way to the end of the barrel and the scope is then adjusted to line up exactly according to the position of the boresight. A gun can only be properly sighted in at a shooting range after it has been boresighted, usually at a distance of 25 yards.

  1. Muzzle attachments

    • The first boresights, which are still used today, attach to the end of the barrel by means of an adjustable attachment which fits into the muzzle of the gun. This piece can be adjusted to fit various barrels snugly, dialing down to fit a .22 rifle or expanded for a .30 caliber rifle or much larger for a shotgun. The piece is fitted into the barrel snugly enough to remove any wobble, and holds the entire boresight in alignment, pointing directly where the barrel is aimed.

    Magnetic attachment

    • Newer boresights attach magnetically. They are also attached to the end of the barrel, but they do not adjust from one gun to another. Rather, the magnetic attachment allows them to be fastened to a gun barrel of any caliber with proper alignment.

    Lens sighting

    • Magnetic boresights and muzzle-attached boresights have a lens that stands up above the profile of the barrel, just beyond the front sight--if there is a front sight. This lens has a crosshair or some other indication for centering the aim alignment. After the boresight is fitted in place, the shooter looks through the scope and adjusts the scope until its crosshairs line up exactly with the markings on the lens of the boresight.

    Laser sighting

    • The newest technology to come to boresighting is the sighting of laser boresighters. These boresights do not attach to the end of the barrel, but slide into the firing chamer itself. They are adjustable for caliber and make, and slide into the chamber from the top of the magazine just like a live round. The laser shines out the length of the barrel. The shooter can then look through the scope and adjust the windage to focus the crosshairs of the scope on the dot that the laser projects.

    Using a boresight

    • Boresights are the first step in aligning a newly installed scope.The boresight is intended to align the scope with the aim of the barrel at a distance of 25 yards. Thus, when using a laser boresighter, you should adjust the scope to a laser-projected dot on a surface 25 yards away. But boresighting does not completely sight in a gun. No matter how accurate a boresight may be, there are always variables in the actual firing of the weapon that cannot be accounted for. Be sure to sight in your gun at a live range after boresighting.