O.K., I asked the question and decided today to go to the best authority I know of: Jack Rowe of Enid, Oklahoma. Jack's response was that some, but not all, of the guns would be shot and regulated BUT only for pattern. Never for point of impact. He discussed with me how difficult, if not impossible, it would be to loosen ribs of a shotgun and reset them. He contrased this with double rifles which are regulated for point of impact but they have a wedge at the muzzle that can be moved to change the impact. Shotguns do not have this feature. He indicated even the best shotguns are not regulated for POI. Jack described the process of joining the barrels and the precision with which they are set up for soldering or brazing using two levels on the jig. He said the bores remain perfectly straight and properly done they will shoot very close together. He also mentioned how useless it is for a maker to regulate POI since so much of it depends on the individual shooter's style. I enjoyed his closing comment: "My goodness, it's a shotgun, not a rifle and it only takes one pellet to kill. The bird's not going to know the difference if one barrel shoots a couple inches from the other."
