text: They were popularized in the 1920s and 1930s as weapon of choice of American gangsters and police , in the form of the famous Thompson submachine gun , commonly referred to as the `` Tommy Gun '' .
simplified: They were popularized in the 1920s and '30s as weapon of choice of American gangsters and police , in the form of the famous Thompson submachine gun , commonly referred to as the `` Tommy Gun '' .