The M3 (officially the Sub-machine Gun, Calibre .45, M3) was an American submachine gun that was designed by George Hyde and produced by the General Motors Guide Lamp Division. It was developed for the US Army during World War II as a cheaper alternative to the expensive Thompson submachine gun.


The Grease Gun was invented by George J. Hyde in December 1942 as a light and simple SMG for the U.S. Army. The gun itself was modeled after the German MP-40 SMG and the British Sten sub-machine gun. The M3 was durable, accurate and resistant to dirt jamming it. However one of the main drawbacks was it could only fire in automatic causing an occasional jam from the ammo feed. Another drawback was the firing rate, which was 450 rpm compared to its predecessor, the M1928 Thompson's 675 rpm. It still came out in front of the Thompson because the M3 used state-of-the-art sheet metal pressing, making it cheap and robust. The Grease Gun was used mainly in the Pacific or by the French Resistance because of its small size and reliability.

Post WWIIEdit

After 1945 the U.S. sold most M3s manufactured to other countries. The gun was used in the US armed forces until 1992 when it was replaced by more modern sub-machine guns and assault rifles. Over 655,000 M3s and other versions have been produced in many countries from Argentina to Taiwan since 1942, and the reliable sub-machine gun was used by many foreign militaries going even up to the 1990s. As of 2004, the Philippines have revived and revamped mothballed stock of M3 Grease Guns, coated with corrosion-resistant camouflage finish, silencers and picatinny rails.


  • Julio S. Guzmán, Las Armas Modernas de Infantería