It is in his book, The Paper Jacket, if memory serves (dangerous assumption).
But here is his technique. It takes two people who are pretty trusting, a really good benchrest, or better, a gun vice, and a 2-way radio.
The idea is simple. Using a black bull the size of your normal sighting target for that distance, put a pin in the exact center of it. A thumbtack will do. But prick a deadcenter hole.
Now, aim the gun/vice/bench at your backstop at the designated yardage and line it up so that the sights are about centered on a clean, smooth backer board.
Have your "shooter," with breech open, sight through the rifle and, using the radio, tell the second person who is at the backstop how to move the target left and right, up and down, quickly (before eyes tire) until it is centered for a shot according to the shooter.
When this has been done, poke the thumbtack through the pin hole in the center of bull and make a hole in the backer board. That's the "shooter's" first "shot".
Remove the bull and w/o touching the rifle or moving it in any way, repeat the process 4 or 9 more times for a 5 or 10 "shot" group.
Measure the group size as the distance between the pin pricks of course.
Does that make sense?
Brent
