Introduction to Boresights
Boresighting aligns the optical sight on top of the gun barrel with the axis of your bore, and should be the first priority after mounting your scope. This ensures that your first shot will be on a large piece of target paper at a distance of about fifty yards. Boresighting not only gives you a reference point from which to actually start sighting in your gun, but saves time, ammunition expense, and occasionally your shoulder from recoil.
Bore sighting will NOT sight in your gun. This must be done by firing a specific type of ammunition at a certain distance.
Boresighting is done by several different methods. The oldest way
is to remove the bolt on a bolt action rifle and look down the bore. Secure
the gun so it does not move, and position it so it is pointing at the bullseye of a target about fifty yards away. Now look through the scope,
and without moving the gun, carefully adjust the elevation and windage turrets
until the reticle is centered on the bullseye. Simple at that. You are sighted
through the bore, or "bore" "sighted." Of course, this is not possible
with many guns such as semi-autos, pumps, lever guns, and most handguns.
The next oldest way to boresight is with a collimator and arbors. Arbors are sometimes called spuds. A collimator is
a device with a graph-paper-like grid in it that is seen when looking through
your scope. It is held in place by arbors inserted into your barrel from
the muzzle end. They are sized for your caliber, and held in place by a
spring or an expanding plug. The user then looks through his scope and adjusts
the windage and elevation turrets so the crosshair is centered on the grid
you see. The spuds must be sized accordingly, and although many collimating boresights come with several arbors, some calibers such as .17, or
shotgun gauges require their own sizes and may not be available.
Another way to boresight, and the most convenient way, is to use
a magnetic boresighter. These simply attach to your muzzle with strong
magnets instead of inserting arbors into your barrel. Some people frown
upon inserting anything into their barrels besides a cleaning rod. Magnetic
bore sighters fit all calibers and gauges, and no other parts are required
that can get lost or damaged. Magnetic boresighters can also be used
to check zero after transporting your guns, or after a drop or hard use.
To do this, sight in you gun and see where your crosshairs end up on your
boresighter's grid. Remember the placement or write it down to check zero
The third and final way to boresight is with laser boresighters.
Some of these project a laser beam from an arbor or spud inserted into your
muzzle, and some have the dimensions of a specific cartridge case that you
simply insert into your gun's chamber and close the action. Laser bore
sighters do require a somewhat reflective target set some distance away
to reflect your laser beam, and a steady hold or a gun vice to more easily
center the scope's crosshairs onto the laser's dot.