A shotgun is supposed to shoot to the bead. How the gun fits you determines where that bead points when you mount the gun properly. The problem people are referring to about barrel regulation is that these companies say half a foot off is within their tolerance. They'll say this even if the two barrels never converge. Yet their standard specification references the bead as being what their allowed variation is measured from.

When you confront them they trot out that nonsense about how it won't shoot as intended if it isn't fitted to you. It's two parts of one puzzle.