• M3 Sub Machine "Grease' Gun
The M3 is an American .45-caliber submachine gun adopted for U.S. Army service on December 12th, 1942, as the United States Submachine Gun, Cal. .45, M3. The M3 was commonly referred to as the "Grease Gun" or simply "the Greaser", owing to its visual similarity to the mechanic's tool.
In 1941, the US Army Ordnance Board observed the effectiveness of submachine guns employed in Western Europe, particularly the German 9×19mm MP 40 and British Sten submachine gun and initiated a study to develop its own "Sten" type submachine gun in October 1942. The Ordnance Department requested the army submit a list of requirements for the new weapon, and Ordnance in turn received a separate list of requirements from both the infantry and cavalry branches for a shoulder fired weapon with full or semiautomatic fire capability in caliber .45 ACP or .30 Carbine. The two lists of requirements received by Ordnance were then reviewed and amended by officials at Aberdeen Proving Ground (APG). The amended requirement called for an all metal weapon of sheet metal construction in .45 ACP, designed for fast and inexpensive production with a minimum of machining and featuring dual full automatic and semiautomatic fire, a heavy bolt to keep the cyclic rate under 500rpm and the ability to place 90% of shots fired from a standing position in full automatic mode on a 6x6 feet target at a range of 50 yards. The benchmark of the time would be the M1928A1 Thompson.
George Hyde of General Motors's Inland Division was given the task of designing the new weapon, while Frederick Sampson, Inland Division's chief engineer, was responsible for preparing and organizing tooling for production. The original T15 specifications of October 8th, 1942 were altered to remove a semi-automatic fire function, as well as to permit installation of a kit to convert the weapon's original .45 caliber to that of 9 mm Parabellum. The new designation for the 9 mm/.45 full-automatic only weapon was the T20. Five prototype models of the .45 T20 and five 9 mm conversion kits were built by General Motors for testing. At the initial military trials, the T20 successfully completed its accuracy trials with a score of 97 out of 100. Four army test boards composed of multiple army service branches independently tested and reviewed the T-20 prototype weapons including the Airborne Command, the Amphibious Warfare Board, the Infantry Board, and the Armored Forces Board. All four branches reported malfunctions caused by the M3 magazine, mostly attributed to defective or jammed magazine followers. The T20 was formally approved by U.S. Army Ordnance for production at GM's Guide Lamp Division in Anderson, Indiana, in December 1942 as the U.S. Submachine Gun, Caliber .45, M3. Guide Lamp produced 606,694 of the M3 variant submachine gun between 1943 and 1945.
Around one thousand M3 submachine guns in caliber 9 mm Parabellum were built by Guide Lamp. These original 9 mm guns, identified by the markings U.S. 9 mm S.M.G. on the left side of the magazine well (without any model designation, such as M3), were delivered to the OSS in 1944. The 9mm M3 was also supply to the French and Norwegian resistance so that captured German ammo could be used. Though 25,000 kits were originally requested for procurement, this was changed to a recommendation by the Ordnance Committee in December 1943 that only 500 9 mm conversion kits be obtained. These conversion kits included a new 9 mm barrel, replacement bolt and recoil springs, a magazine well adapter for use with British Sten gun 32-round magazines, and a replacement 9 mm Sten magazine of British manufacture. The OSS also requested approximately 1,000 .45-caliber M3 submachine guns with an integral sound suppressor (designed by Bell Laboratories). Specially drilled barrels and barrel nuts were manufactured by Guide Lamp, while the High Standard Firearms Company produced the internal components and assembled the weapon. With its stamped, riveted, and welded construction, the M3 was originally designed as a minimum-cost small arm, to be used and discarded once it became inoperative. As such, replacement parts, weapon-specific tools, and sub-assemblies were not made available to unit-, depot-, or ordnance-level commands at the time of the M3's introduction to service. In 1944, a shortage of M3 submachine guns created by the need for interim production changes forced U.S. Army Ordnance workshops to fabricate pawl springs and other parts to keep existing weapons operational.
After its introduction to service, reports of unserviceability of the M3 commenced in February 1944 with stateside units in training, who reported early failure of the cocking handle/bolt retraction mechanism on some weapons. Similar reports later came from U.S. forces in Britain who were issued the M3. The M3 submachine gun was suitable for the US army to be issued to tank crews, drivers and paratroopers because of its compact design. The M3 was also suitable for the US army in the Pacific War because the Thompson could easily jam if not cleaned which had to be done constantly in the jungle environment because the action of the Thompson did not have a cover over the ejector as the M3 did. In December 1944, in response to field requests for further improvements to the basic M3 design, an improved, simplified variant of the M3 was introduced, the M3A1. 15,469 M3A1 submachine guns were produced before the end of World War II, and 33,200 during the Korean War. It was originally hoped that the M3 could be produced in numbers sufficient to cancel future orders for the Thompson submachine gun, and to allow the army to gradually withdraw the more expensive Thompson from front-line service. However, due to unforeseen production delays and requests for modifications, the M3 was introduced later than expected, and purchases of the Thompson continued until February 1944. The M3A1 did not see combat in World War II, but was used in the Korea War and the Vietnam War.The M3 and M3A1 were largely withdrawn from U.S. frontline service beginning in 1959 and into the early 1960s, but continued to be used until the mid-1990s as on vehicle equipment aboard armored vehicles.
