Andreas,

i hate to say anythng as I usually end up stcking my foot in my mouth but here goes. We would shoot four and six shot groups and determine the average then make an adjustment. I would start with clean dry bbls and try to shoot the shots at a steady pace. Not rushng but not didlng around either. Dad would mark the shots with the spottng scope and mark them on a target at the bench then back at the shop we would measure the shots on the actual target. This last gun would always shoot one hole wth the right bbl. but the left group would always be larger. Still, it took us forever. :^)