[carsonbm]

What is boresighting. Please keep it simple.

[Outlaws]

http://www.chuckhawks.com/bore_sight.htm

[Vern Humphrey]

In boresighting, the bolt is removed and the rifle is pointed at the target by looking through the bore. With the rifle firmly braced, and the target centered in the bore, the sights are adjusted so they also point at the target.

There are several variations on this -- lncluding using a laser or collimator -- but the principle is the same.

It is still necessary to shoot the rifle to determine the final zero, but boresighting will get you on the paper. In some applications, such as guns mounted on aircraft, the "jump" (difference between boredsighted point of aim and actual point of impact) is known, and boresighting is all that is needed.

[EShell]

Definitely necessary to shoot to get the zero correct, but if you have a reference and a collumnator, you can get very close.

I use my boresighter when changing optics. I take a reference with the existing scope, remove it and install the new scope and simply dial it to the same reference. Usually, it's within inches at 100yards.

I have references for all of my rifle's 100 yard zeros, so that I can check or change things easily just using the boresighter.