This thread got me to thinking.
Sunday morning I was up north and decided to sight in my 22 mag that I had just repainted and mounted a new scope on. After we had set up a target at 100yds, I took the rifle out and to my dismay, noticed that I had forgot to boresight it, and did not the have boresighter with me.
We did not feel like trudging through the 16-18" of snow again to move the target closer, so we proceeded to use the method as described by Pilot195 above. Well let's just say it ended up taking about 17 shots to get it to my liking. Printing a final 3 shots of 3/8".
It was kind of an irritating process and I cursed myself for not boresighting before I left home. But I have done it many times before, and it worked.
Sooooo, I just now stuck the boresighter in the 22 mag, and guess what? Windage is dead on, as in not even one click off. Elevation is only 4-5 clicks off.
In other words, the boresighter would have easily had me on paper @ 100yds in this case also, and saved me some ammo......