While on the subject of the Colt Thompson 1921, both 50 and 100 rd drum magazines were manufactured. Big customers for the 100 rd drum were both the I.R.A. and the US Post Office Dept. Post Office purchased both the Colt Thompson and 100 & 50 rd drums to supply the US Marines who were used to guard the mail trains in NY. A few years later the USMC returned some of this equipment but continued to use the Colt Thompson and large drums during the small "Banana Wars" during the late 1 920's and 30's.

Gangsters continue to favor the large 100 rd drum magazines during the 1930's