I was watching the "St. Valentine's Day Massacre" on the History channel. it was said that the Capone's guys made one run on the "hitee" using blanks in the Thompsons. then after the "hitee" had relaxed little bit they made another run using real ammo and really made a mess of things. I have always been under the impression that to make most guns work with blanks that something had to be done them to let them feed and cycle properly. I can't imagine having two sets of guns so was the Thompson different?