I bought an Auto-Ordnance Model 1927 M1 "Tommy Gun."
Why? Because I could!
My father used one in Vietnam, he was on a minesweep off the coast and was in charge of the boarding party. They used to search junks and other Vietnamese boats for weapons. He had an idiot captain that told him he could not have his men chamber rounds when boarding. So my father logged that he obeyed under protest and when he boarded he just cocked his Thompson. HaHa, its an open bolt weapon! He can't chamber a round! The captain never knew.
Of course, mine is a current production closed bolt design.
Another interesting note, my father volunteered for the Swift boats, but got to Vietnam after they turned ops over to the South Vietnamese (68-69?). Scary, he might have been a shipmate with John F*@$ Kerry.