I bought one off a friend. It was his father's gun made in the mid 50's and looked like it just came off the assembly line.
I didn't know what a "riot gun" was until one day, at the range, a police officer's eyes got big and bulgie when he saw the gun.
He told me to load it up and hold the trigger back while I pumped it ------ Fast. I learned what a "riot gun" was in the next few seconds.