You are wrong, Piers Morgan said it was an “AR-15 shotgun.” He didn’t specify if was either the automatic or the assault shotgun version though.
Speaking of automatic shotguns.
My Dad bought a Belgium Browning 12 gauge Semi automatic modified long barrel shot gun, with the gold trigger back in the 1950’s. He used it for bird hunting mostly. It was too heavy for much else, at least that was my opinion. My younger brother owns it now. However, it would sometimes fire off TWO or THREE shells when you only pulled the trigger once. My father sent it back to have it repaired at a factory authorized gunsmith. He said it only did it sometimes. It would scare the heck out of him.
So in a way it was a automatic shotgun.