Thompson M1919/20 Prototype No.8 
Thompson M1919/20 Prototype No.8. Thompson M1919/20 Prototype No.1.
The M1919 is a family of various Thompson submachine gun prototypes, all slightly different from each other. Around 40 prototypes were believed to have been made, and only 11 exist today. The earliest M1919 Thompsons (after the “Persuader” prototype) are also known as “Annihilators”. The earliest Annihilator I needed an adaptor to use straight magazines.
The SMGs appear in various configurations, with different attachments, and some lacking sights and buttstocks.
Contrary to popular myth, the “Annihilators” were never intended to be shipped to WWI-era Europe, because there was only one example of the Annihilator in 1918, and was still testing its magazine feed system at the time. With a few exceptions, Auto-Ordnance only began attempting to market their weapons later in 1920, to the Polish and anti-Bolshevik forces at war at the time, but intense hostilities interrupted these plans. The “WWI-myth” itself stems from the 1921 confiscation of a M1921 batch destined for the Irish Republican Army from the New York docks. 
M1919 Thompson serial number 17 as it appears in early sales literature, with 50-round drum magazine (20-round box and 100-round drum beside) - .45 ACP 