Years ago I saw a movie about a guy who was nuts and thought he was the leader of this big crime family but in the end he was strapped to a table and they told him that it was just him acting alone all along. One scene in particular I remember he climbs up the side of a building with the Tommy gun and airs out this whole apartment. I thought the movie was called crazy Joe but I just read the plot for crazy Joe on IMDB and this is not the movie in question.

Does anyone know the name of the movie I'm referring to? Its been bothering me all morning.