M3 Grease Gun
Guide Lamp Division, General Motors · Submachine Gun · Discontinued · 1943
Also known as: Grease Gun, The Greaser, Cake Decorator, U.S. Submachine Gun, Cal. .45, M3
Overview
The M3 submachine gun, universally known as the 'Grease Gun' for its resemblance to the mechanic's tool, is an American .45 ACP submachine gun designed by George Hyde and Frederick Sampson in 1942 as a cheaper and simpler replacement for the Thompson submachine gun. Manufactured by the Guide Lamp Division of General Motors in Anderson, Indiana, the M3 was built almost entirely from stamped steel components assembled by spot welding, requiring only 73 parts of which just two (the bolt and barrel) needed precision machining. Adopted in January 1943 after an extraordinarily rapid seven-month development cycle, it cost approximately $21 per unit compared to $45 for the Thompson. Firing from an open bolt via simple blowback operation, its relatively low cyclic rate of 450 rounds per minute made it more controllable than many contemporary submachine guns. Despite initial skepticism from soldiers accustomed to the Thompson, the M3 and its improved M3A1 variant served the United States military for over fifty years, seeing combat from Normandy through the Korean and Vietnam Wars, and remaining in armored vehicle crews' inventories into the 1990s.
Specifications
| Weight (empty) | 3630 g (128.0 oz) |
| Weight (loaded) | 4490 g (158.4 oz) |
| Overall Length | 757 mm (29.80") |
| Folded Length | 579 mm (22.80") |
| Barrel Length | 203 mm (7.99") |
| Height | 140 mm (5.51") |
| Width | 34 mm (1.34") |
| Sight Radius | 276 mm (10.87") |
| Action Type | Blowback |
| Firing Mechanism | Open Bolt |
| Trigger Type | Single Stage |
| Trigger Pull | 32 N (7.2 lbf) |
| Magazine Capacity | 30 rounds |
| Magazine Type | Detachable Box |
| Muzzle Velocity | 280 m/s (919 fps) |
| Muzzle Energy | 596 J (440 ft·lbf) |
| Effective Range | 91 m (100 yd) |
| Maximum Range | 695 m (760 yd) |
| Rate of Fire | 450 rpm |
| Barrel Rifling | Right Hand |
| Rifling Twist | 406 mm (15.98") |
| Number of Grooves | 4 |
| Frame Material | Steel |
| Barrel Material | Steel |
| Stock Material | Steel |
| Finish | Parkerized |
Calibers
- .45 ACP · primary — also known as .45 Auto, 11.43x23mm, .45 Automatic Colt Pistol
Features
- Firing modes: Full Automatic
- Feed systems: Detachable Box Magazine
- Safety mechanisms: Ejection Port Dust Cover
- Features: Open Bolt Firing, Stamped Receiver, Collapsible Wire Stock, Simple Construction, Spot Welded Assembly, 9mm Conversion Kit Available
Variants
- M3A1 — Improved
- M3 (9mm OSS Conversion) — Caliber Conversion
- M3A1 Suppressed (Bell Labs) — Suppressed
- PAM 1 — Argentine Variant
- PAM 2 — Argentine Variant
- Type 36 — Chinese Copy
Service history
Operators
- United States Army · adopted 1943 · as U.S. Submachine Gun, Cal. .45, M3
- United States Marine Corps · adopted 1943 · as M3
- Argentine Armed Forces · as PAM 1 / PAM 2
- Republic of China Army · adopted 1947 · as Type 36
- Republic of Korea Armed Forces · as M3A1
- Philippine Armed Forces · as M3
- Japanese Self-Defense Forces · as M3A1
- Bolivian Armed Forces · as M3
Conflicts
- World War II (1943-1945)
- Korean War (1950-1953)
- Vietnam War (1955-1975)
- Chinese Civil War (1945-1949)
Production
Estimated total produced: 655,363 · Production years: 1943-1945, 1951-1952
606,694 M3 units produced during WWII by Guide Lamp Division; 15,469 M3A1 units produced during WWII; 33,200 M3A1 units produced by Ithaca Gun Company during the Korean War. Total WWII production was 622,163 units.
Origin
Country of origin: United States
Designer: George Hyde
Discontinued: 1945
Notes
The M3's ejection port dust cover doubles as its only safety mechanism -- when closed, it physically blocks the bolt from moving forward. The collapsible wire stock could be removed and used as a barrel wrench and cleaning rod. The M3A1 variant (December 1944) eliminated the fragile crank-type cocking handle, replacing it with a finger hole in the bolt for direct charging. Approximately 1,000 units were produced in 9x19mm Parabellum for the OSS, and Bell Laboratories developed a suppressed version with a drilled barrel and expansion sleeve for special operations. Nearly 20,000 M3 receivers were rejected during production due to manufacturing defects from excessive heat during welding. Cost per unit was approximately $20.94 ($313.62 in modern dollars).
Background
The M3 was designed and put into production in just seven months, an astonishingly short timeline for a military weapon. Paratroopers of the 82nd and 101st Airborne Divisions carried it during the D-Day invasion of Normandy on June 6, 1944. Despite being designed as a disposable wartime expedient, the Grease Gun outlasted its more famous predecessor, the Thompson, in U.S. service by decades. Tank crews especially favored it for its compact size with the stock collapsed, and late-model Sherman tanks were fitted with up to five M3 submachine guns. Medal of Honor recipient T/Sgt Charles F. Carey used an M3 to single-handedly persuade 30 to 40 German soldiers to surrender at Rimling, France on January 8, 1945. The weapon's homely appearance led to its derisive nicknames, but its reliability and ease of maintenance earned grudging respect in the field.