The "standard" for adjusting an Einstecklauf = insert barrel is adjusting it to the sights at that range it is most likely to be usefull. The main rifle barrel of a drilling or combination gun may shoot to the sights at 150 or 200 yards, but the insert is most likely to be used at small targets at much shorter ranges. So it should shoot to the sights at 100 yards for a .22 Hornet or a .22 Magnum rimfire, but at only about 50 yards for a .22 lr. Adjust it to shoot to your sight at these ranges, not to shoot in the same group as the main barrel. Making it to group with the main rifle barrel is quite useless, as the trajectory of the large and the small bore cartridges will be quite different anyhow. F.i. if a .22lr insert shoots into the same group with a 7x65R main barrel at 100 yards, it will be useless at the much shorter ranges it is of any use because of the high trajectory of a .22lr over 100 yards.