The Thompson submachine gun is one of the most iconic weapons in American history. When manufacturers struggled to meet military demand during WWII, General Motors came up with a solution, the M3A1 “Grease Gun.”
The M3 is a .45 caliber sub-machine gun like the Thompson, but was cheaper to produce. Roughly 10 M3s could be produced at the same cost of a single Thompson. The M3 was soon called a “grease gun” or “greaser” for having a similar visual appearance to a mechanic’s tool.
Although yearly US army training films claimed the M3 was more accurate than the Thompson, the reverse was actually true.
The M3 saw limited use in WWII, but remained in use from 1943 through 1992.
See it in action with the boys from Moss Pawn & Gun in the video below.
Bonus trivia, the M3’s flared flash suppressor was used by the prop department to build Han Solo’s DL44 blaster in Star Wars: A New Hope.