M1A1 Thompson

There are two basic types of Thompson Submachine Guns the 1921/1928/1928A1 and the M1/M1A1. The 1st Model Thompson was the 1921 or gangster gun.  Minor modifications were made to this weapon which changed the designation from the 1921- 1928 to 1928A1. All three of these models are virtually the same weapon with all parts being interchangeable.  Some of the common features of this model are the drum magazine, the top mounted bolt handle and the Cutts compensator at the end of the barrel.   Early in WWII, the Thompson was redesigned to create the M1 and M1A1 models. The distinctive feature of these two new models are the side mounted bolt handle, fixed butt stock, and the none adjustable stamp rear sight.  Both models were used during the second World War in both the European and Pacific theaters.  Production of the Thompson was terminated sometime during WWII at which time the company became defunct. It was replaced by M3 grease gun which was cheaper and easier to manufacture and could be mass produced in a short period of time.

Ref: The Thompson by D. Richardson. 

The picture on the left shows early parachute troops with their 1928 Thompsons. The picture on the right taken in Germany 1945 shows  Ken Kochenour of C Company 502 PIR  with his M1A1 Thompson. Standing next  to  Kochenour is Wiley Myers with his M1.  The difference in each model Thompson are easily seen in these pictures.