Impossibru, the tommy gun was made at the end of WW1.
The M1 Garand (officially designated as United States Rifle, Caliber .30, M1 and later simply Rifle, Caliber .30, M1, and also abbreviated as US Rifle, Cal. .30, M1), was the first semi-automatic rifle to be generally issued to the infantry of any nation
-Wikipedia
And apparently, the M1 Thompson was designed in 1938.