I am guessing these shotguns fall in the same catagory as the Ithaca model 37 Stakeout with a 13" barrel and a pistol grip stock and were legal to buy and own for a simple $5 transfer fee. And they were legal because they were factory made this way. And I am going on my memory of a Guns & Ammo article on the guns written long ago.
If anyone remembers the 80's TV show Miami Vice the character named "Tubbs" used a model 37 Stakeout to back up whatever snubby revolver he carried. And the model 37 had the unique feature that allowed you to fire the gun by holding the trigger back and pumping the forearm. As soon as the action closed it would fire.
https://www.militaryfactory.com/smallarms/detail.asp?smallarms_id=107
If anyone remembers the 80's TV show Miami Vice the character named "Tubbs" used a model 37 Stakeout to back up whatever snubby revolver he carried. And the model 37 had the unique feature that allowed you to fire the gun by holding the trigger back and pumping the forearm. As soon as the action closed it would fire.
https://www.militaryfactory.com/smallarms/detail.asp?smallarms_id=107