Gunman;
The only other comment I would have here & this is likely still a matter of terminology.
As I understand the word "Regulate" as applies to either a dbl shotgun or rifle, it simply means to so align the bbls as to shoot to the desired point of impact.
I would likely have to dig through a lot of old writing, but am pretty certain that I have read references of better makers of dbl shotguns firing their guns & if the bbls did not center their charges together, they would melt the solder from the ribs etc & "Regulate" them & re-solder.
Perhaps over the years enough experience has been gained on the original setting that this is no longer felt to be a need. Judging from your list of credentials you should certainly have more knowledge of this than me.
I do know though that I am not just dreaming it up, that at least in times gone by some makers have "Regulated" the barrels of their double shotguns, or at least they stated they did.
PS; Even the initial setting of the bbls to a predetermined convergence would in my definitation of the word be considered regulation, even though it was never altered.
