First & Foremost "NO" reputable gunmaker built that reputation by putting out guns of which the Surer your hold the more certain you were to "Miss". To say those barrels were not "Tweaked" after their original assembly is one thing. To say they were totally Sans Regulation is another thing altogether. They were by design assembled in such a predetermined way as to within reason assure they would Hit with reasonable accuracy for a shotgun to the same point of aim. That in & of itself is regulation. From what knowledge I have seen in the past "Long Before the Internet" many gunmakers did maintain an in House shooting range & did fire their guns for both pattern & placement. No doubt only in severe cases was any further action needed, & even then no doubt a few slipped through the cracks, as witnessed by Joe's gun.
To imply as gunman did that the only consideration was that the muzzles touch with total disregard as to whether they shot to point of aim, I simply Cannot & Do Not accept. As I said in an earlier post on this same thread Not All SxS doubles left the factory with the muzzles touching. It is not uncommon to find a short barreled gun built on a wide frame with a factory installed keel between the barrels at the muzzle. Why, well simple, to have placed them together would have created a cross firing gun.

Miller/TN
I Didn't Say Everything I Said, Yogi Berra