I heard that a reporter shot a modern sporting rifle after the Orlando massacre just to see what it was like. He actually reported that it bruised his shoulder and that he now suffers from PTSD. I don't have a link but this actually happened.
So obviously, the concussive waves of the respective shots in that enclosed space rendered the victims into immobile statues instantaneously.
I'd pay good money to see this "reporter" donkey kicked by a 12 gauge.
There is a 4-page long thread on it here on this site: AR-15: It feels like a bazooka and sounds like a cannon (https://www.northwestfirearms.com/threads/ar-15-it-feels-like-a-bazooka-and-sounds-like-a-cannon.221721/)