M3 submachine gun
The inexpensive, stamped-steel 'Grease Gun' that replaced the Thompson.
The M3 is an American submachine gun firing .45-caliber ammunition, officially adopted by the U.S. Army on December 12, 1942, under the designation United States Submachine Gun, Cal. .45, M3. It used the same .45 ACP cartridge as the Thompson submachine gun but was less expensive to mass-produce and weighed less, though it was less accurate. Its resemblance to a mechanic's grease gun earned it the nicknames "Grease Gun" or "the Greaser." Designed to replace the Thompson, the M3 began reaching frontline troops around mid-1944. A variant, the M3A1, was introduced in late 1944 and continued to see service in the Korean War and later conflicts.
The M14 rifle, adopted in 1959, was meant to replace the M3A1 along with the M1 Garand, M1918 Browning Automatic Rifle, and M1 carbine, but the recoil of its 7.62×51mm NATO round proved too strong for the submachine gun role. The M14 was itself replaced by the M16 rifle in 1964, and the M16’s shorter versions, like the XM-177 firing the intermediate 5.56×45mm NATO cartridge, served as a better substitute for the M3A1. The M3A1 was withdrawn from frontline U.S. service after 1959 but remained in use as a backup weapon, for instance by armored vehicle crews as late as the Gulf War (1990–1991). Many overseas U.S. military bases continued issuing it to certain crews into the mid-to-late 1990s.
In 1941, the U.S. Army Ordnance Board noticed how effective submachine guns were in Western Europe, especially the German 9×19mm MP 40 and the British Sten, and in October 1942 began studying how to develop its own Sten-like submachine gun. The Ordnance Department asked the Army for requirements, and both the Infantry and Cavalry branches submitted separate lists calling for a shoulder-fired weapon with full or semiautomatic fire in .45 ACP or .30 Carbine. Officials at Aberdeen Proving Ground reviewed and amended these lists, demanding an all-sheet-metal weapon in .45 ACP designed for quick, cheap production with minimal machining, offering both automatic and semiautomatic fire, a heavy bolt to keep the cyclic rate under 500 rounds per minute, and the ability to place 90% of shots from a standing position in full auto on a 6x6-foot target at 50 yards. The M1928A1 Thompson would serve as the benchmark for testing.
Quick Facts
- Origin
- United States
- Is Ranged
- yes
- Service
- 1943–present
- Designer
- George Hyde
- Design Date
- 1942
- Manufacturer
- General Motors, others
- Production Date
- 1943–1945; early 1950s
- Number
- Total: 655,363 / M3: 606,694 / M3A1: 48,669
- Variants
- M3A1 / PAM1 / PAM2 / T29
- Weight
- M3 (empty): 8.15 lb / M3A1 (empty): 7.95 lb
- Length
- 29.1 in stock extended / 21.9 in stock collapsed
- Part Length
- 8 in
Facts from the source article.
Lore & Background
The M3's development began in October 1942 after the U.S. Army Ordnance Board observed the effectiveness of submachine guns in Western Europe, particularly the German MP 40 and British Sten. George Hyde of General Motors' Inland Division designed the weapon, with Frederick Sampson overseeing tooling for production. The original T15 specifications were altered to remove semi-automatic fire and to permit a 9 mm conversion kit, resulting in the T20 designation. Five prototypes were built, and after trials the T20 was approved for production in December 1942 as the M3. The M3 featured all-sheet metal construction with stamped, riveted, and welded parts, designed to be inexpensive and disposable. Early service reports from February 1944 revealed deficiencies in the cocking mechanism, barrel retention, and rear sight, leading to several product improvements. The M3A1 variant was introduced in December 1944; 15,469 were produced before the end of World War II, and an additional 33,200 during the Korean War.
Reader's Guide
The M3 was intended as a cost-effective replacement for the Thompson submachine gun, and its production was hoped to cancel further Thompson orders. However, production delays and modification requests meant the Thompson continued to be purchased until February 1944. The M3 saw frontline service from mid-1944 and was used in the Pacific War, where its covered ejector offered an advantage over the Thompson in jungle conditions. The M3A1 variant saw use in the Korean War and later conflicts. The M14 rifle, adopted in 1959, was intended to replace the M3A1 but its 7.62×51mm NATO cartridge proved too powerful for the submachine gun role. The M16 rifle and its shorter iterations (XM-177) firing 5.56×45mm NATO were better replacements. M3A1 submachine guns were retired from U.S. frontline service after 1959 but continued to be issued as backup weapons for armored vehicle crews as late as the Gulf War (1990–1991), and many overseas U.S. military bases continued to issue them for certain crews into the mid to late 1990s.
Did You Know?
- The M3 was commonly called the 'Grease Gun' due to its resemblance to a mechanic's grease gun.
- Around 1,000 M3 submachine guns in 9 mm Parabellum were built for the OSS and supplied to resistance groups in Europe.
- The M3 was originally designed to be discarded once inoperative, with no replacement parts or tools initially made available.
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