Bushnell Magnetic Bore Sighter
By Chuck Hawks
Optical boresighters are handy devices. They are generally shaped roughly like a truncated cone, with an optical bell about 3.25" long. There is a lens in the big end--the end that points at the objective of the rifle's scope. Inside the boresighter there is a grid with heavier lines forming a cross at the center of the grid. The idea is to center the crosshairs of the scope on the center cross in the boresighter. Then the rifle has been boresighted and should at least hit the paper at 25 yards when you take it to the rifle range to actually zero it in.
Traditional boresighters, including those made by Bushnell in the past, have used a selection of expanding spuds that are inserted into the rifle's bore and tightened to hold the boresighter in place. But not any more.
The Bushnell Magnetic Boresighter looks just like the spud kind, but it sticks to the end of the gun barrel by means of a powerful magnetic strip below the optical bell of the device. This magnet held the boresighter firmly in place at the end of every rifle barrel on which I tried it, from .22 caliber to .50 caliber, including stainless steel barrels. It will also work on handguns and shotguns equipped with adjustable sights. It is simple and faster to use than the previous type of optical boresighter, and you will never be caught without the proper spud.
Bushnell claims that the Magnetic Boresighter can be used with red dot optical sights and even adjustable iron sights, as well as telescopic sights. It is designed to work with all magnifications, although higher magnification will allow the user to see more detail. I have used it with scopes ranging from 1x to 25x without a problem.
Needless to say, optical boresighting is simpler and faster than the old fashioned method of actually looking down the bore of a rifle at a distant object and adjusting the sights to align on that object. If you are interested, you can read about how to bore sight a rifle the old fashioned way in my article "How to Bore Sight a Rifle."
The Magnetic Boresighter is so easy to use that there are really only three steps involved, although Bushnell adds three additional steps (that are so obvious they should be unnecessary). Let me quote the Bushnell instruction sheet supplied with the device:
1) "Using the built-in magnet on the boresighter, attach the boresighter to the end of the barrel. The lens on the boresighter should be at roughly the same height as the bell of the scope."
2) "Look through the scope at the boresighter's crosshairs. This boresighter is designed to work at all magnifications, although higher magnification will let you see more detail."
3)"Adjust your crosshairs so that they point at the center of the grid."
4) "Remove the boresighter from the firearm"
5) "Shoot your firearm and make any final adjustments."
6) "Once you have zeroed your rifle, you can record your zero for reference by writing down where the crosshairs point on the grid. This way, if you ever want to check your zero without going to the range of if you install a different scope on that firearm, you can quickly get to exactly where that rifle shoots."
Steps 1 through 3 should get your firearm boresighted, but don't forget step #5. Bore sighted is not sighted-in. It may not (and probably won't) get you on the paper at 100 yards.
After boresighting, get to a range and do your initial shooting at 25 yards. If you have boresighted correctly your bullets should hit somewhere on the paper at that distance. If you are shooting a centerfire rifle, zero it dead on at 25 yards. Then move back to 100 yards. Now your bullets should be hitting the paper at 100 yards, and you can zero your rifle for its maximum point blank range, or however you prefer.
At this writing, the Bushnell Magnetic Boresighter sells for about $30 at the sporting goods department of my local discount department store. If you own several rifles, it is money well spent.
Copyright 2004, 2013 by Chuck Hawks. All rights reserved.