I would like to say hello I have been lurking for some time first time posting there is a lot of great info on here and I wanted to add my 2 cents to this post.
When a double barrel shotgun fires both barrels with one pull of the trigger it is called doubling. Both barrels don't actually fire at the same time, the recoil from the first round releases the defective lock on the second barrel. Even if it was intentional modified to fire both barrels with one pull of the trigger it would not be considered a MG since it is incapable of reloading the chambers "automatically"
When a double barrel shotgun fires both barrels with one pull of the trigger it is called doubling. Both barrels don't actually fire at the same time, the recoil from the first round releases the defective lock on the second barrel. Even if it was intentional modified to fire both barrels with one pull of the trigger it would not be considered a MG since it is incapable of reloading the chambers "automatically"