This is another future article for your review. As always, comments are welcome. Many of you, like me, have had hands-on experience with this submachine gun in the military. Hope you enjoy it.
John
U.S. M3 and M3A1 submachine guns
As World War II began and as the United States entered the war on December 7, 1941, our country’s inventory of military weapons was sadly lacking. Not the least of our problems was that our main submachine guns, the Thompsons, had origins dating back to the early 1920s. These were excellent and reliable guns, but quite heavy with forged steel frames and not really suited for mass production. In the meanwhile, the Germans had developed a second generation of submachine guns, the folding stock MP 38 and the subsequent similar MP 40. These could be turned out rapidly because of their stamped sheet steel receivers, and were considerably lighter than our Thompsons. Being compact when their stocks were folded, they were also better suited for cramped quarters such as inside tanks. The British were using U.S.-manufactured Thompsons, but saw the German precedent and began to manufacture their own somewhat crude but lightweight Sten submachine guns in 1941. Both the German and British guns fired the standard European 9mm Parabellum cartridge. In the United States, Thompson production could not keep up with demand, so our military went to work designing our own lightweight stamped steel subgun that would be chambered in our standard .45 ACP caliber. The result of these efforts was the M3 submachine gun. Because of its obvious similarity to a common automotive lubrication tool, it was quickly nicknamed the “grease gun.”
In October 1942, the U.S. Army Ordnance Board, seeing the trend set by the German MP 38s and MP 40s and the British Stens, began a study to develop a similar gun for the U.S. Originally it was to fire either the .45 ACP or .30 Carbine cartridges either in full-auto or semiautomatic mode. However, the Aberdeen Proving Ground found the carbine cartridge too powerful for a blowback weapon locked only by the mass of the bolt and the power of its recoil springs. The semiautomatic requirement was later dropped, due to a slower rate of fire in the full-automatic mode. George Hyde of General Motors’ Inland Division was instrumental in developing the design. Frederick Sampson, Inland Division's chief engineer, was responsible for all tooling and production.
The .45 caliber M3 subgun was formally adopted quickly in December, 1942, and was a startling departure from the Thompsons. It cost the government about $20.00 in 1943 dollars. Its receiver was crafted into a tube shape from stamped and welded heavy gauge sheet steel. The trigger and retractor housings were likewise made from sheet steel. The 8-inch barrel was screwed into the front of the receiver. The heavy steel bolt was backed by twin recoil springs, and the firing pin was nothing more than a projection machined into the face of the bolt. The gun was a straight blowback design made to fire from an open bolt. Pulling the trigger released the bolt to jump forward, stripping a round from the magazine, chambering it, and firing it as it slammed home. Firing in full automatic mode only, the gun would continue to fire as long as the trigger was depressed and there were cartridges in the magazine. The sear would hold the bolt to the rear when the trigger was released unless the ammo in the magazine was exhausted, at which point the bolt would be in the forward position. The bolt could be retracted manually by a prominent spring-loaded lever assembly on the right side of the receiver. A spring-equipped ejection port cover was employed, and when placed down over the ejection port, it served as a safety. The sights were fixed; the rear sight was a simple stamping with an aperture in it. A retractable heavy wire shoulder stock was employed.
While the gun was chambered for the .45 ACP cartridge, it could be easily converted to 9mm with the use of a magazine adapter and changing out the bolt and barrel with 9mm versions. The M3 fed from a 30-round double-column single-feed magazine, mimicking the type used on the Stens. These were not quite as reliable as the double-position feed of the Thompsons, which required less energy to strip a round into the chamber. The rate of fire was a comparatively slow 350 – 450 rounds per minute, compared to some models of the Thompson, which could push to 725 RPM. With its slower cyclic rate, the M3’s trigger could be “tapped off” for single shots if needed. The gun weighed 8.15 pounds, compared to the Thompsons, which weighed from 10.45 to 10.75 pounds, depending on the model. Overall length with the stock extended was 29.8 inches, and when pushed forward, the total length was a handy 22.8 inches, making it very suitable for tank, engineer and aviation crews. The gun could be slung using the standard M1 carbine canvas sling.
The M3 was used throughout World War II, supplementing the more prevalent Thompsons which remained the standard SMGs. The “grease gun” was generally satisfactory but it had one main design flaw. The retracting lever mechanism was both complex and somewhat fragile, resulting in some unfortunate failures in combat. The solution to the problem in December, 1944 was both simple and ingenious. In the newer M3A1, the retracting lever was dispensed with entirely, replaced by a single finger hole for the right forefinger in the bolt, accessible through a larger ejection port. Inserting a finger into this hole allowed the user to retract the bolt back so it could be caught by the sear. Another nice touch for the newer gun was that the bolt and recoil springs could be removed for cleaning from the front by simply unscrewing and removing the barrel. The older M3 required removing the retractor housing from the upper receiver for this. Additional changes were a stock plate and magazine filler being added to the wire stock, and an oil can incorporated into the pistol grip. A longer barrel ratchet spring was used for more positive retention of the barrel, and the magazine catch was provided with a guard to help prevent inadvertent release of the magazine. Weight of the M3A1 was a reduced 7.95 pounds. The gun illustrated for this article is one of the original WWII M3s. The M3A1 saw little (if any) combat action during WWII, but was used extensively in Korea and Vietnam.
The Guide Lamp division of General Motors made approximately 646,000 M3s and M3A1s from 1943 to 1945 during WWII. A version of the M3 that incorporated a sound suppressor in the barrel was developed, with about 1,000 being produced during the war for the OSS (Office of Strategic Services), the forerunner to the present day CIA. After the war, a curved barrel was developed for clearing tanks and transport vehicles from the inside and for shooting around corners. A cone-shaped flash hider was also developed, suitable for both the M3 and the M3A1. About 33,200 M3A1s were produced by the Ithaca Gun Company of Ithaca, New York during the Korean War to supplant those guns left over from the WWII era.
M3s and M3A1s, sometimes produced outside the U.S., have been used by 18 other nations at one time or another. M3A1 submachine guns continued to see some use by our armed forces into the late 1980s, and as late as the Gulf War were still in inventory with engineer units attached to the 1st Armored Division. Originally designed to be cheaply made and thrown away when worn out, they were a surprising mainstay component of our combat forces for many years. Collectors of Class III (legal full-auto firearms) treasure them. Such collectors should be prepared to part with thousands of dollars, endure federal paperwork, and purchase a federal tax stamp. All this to own a gun that originally cost about $20.00! Some semiautomatic look-alikes with longer legal 16.5-inch barrels have been made for those without the inclination and/or funds to purchase the originals. Some semiautos in “pistol” form with no stocks have been made with 8-inch barrels. The originals occupy a milestone position in historic U.S. small arms weaponry, and are indeed classics.
(c) 2016 JLM
John
U.S. M3 and M3A1 submachine guns
As World War II began and as the United States entered the war on December 7, 1941, our country’s inventory of military weapons was sadly lacking. Not the least of our problems was that our main submachine guns, the Thompsons, had origins dating back to the early 1920s. These were excellent and reliable guns, but quite heavy with forged steel frames and not really suited for mass production. In the meanwhile, the Germans had developed a second generation of submachine guns, the folding stock MP 38 and the subsequent similar MP 40. These could be turned out rapidly because of their stamped sheet steel receivers, and were considerably lighter than our Thompsons. Being compact when their stocks were folded, they were also better suited for cramped quarters such as inside tanks. The British were using U.S.-manufactured Thompsons, but saw the German precedent and began to manufacture their own somewhat crude but lightweight Sten submachine guns in 1941. Both the German and British guns fired the standard European 9mm Parabellum cartridge. In the United States, Thompson production could not keep up with demand, so our military went to work designing our own lightweight stamped steel subgun that would be chambered in our standard .45 ACP caliber. The result of these efforts was the M3 submachine gun. Because of its obvious similarity to a common automotive lubrication tool, it was quickly nicknamed the “grease gun.”
In October 1942, the U.S. Army Ordnance Board, seeing the trend set by the German MP 38s and MP 40s and the British Stens, began a study to develop a similar gun for the U.S. Originally it was to fire either the .45 ACP or .30 Carbine cartridges either in full-auto or semiautomatic mode. However, the Aberdeen Proving Ground found the carbine cartridge too powerful for a blowback weapon locked only by the mass of the bolt and the power of its recoil springs. The semiautomatic requirement was later dropped, due to a slower rate of fire in the full-automatic mode. George Hyde of General Motors’ Inland Division was instrumental in developing the design. Frederick Sampson, Inland Division's chief engineer, was responsible for all tooling and production.
The .45 caliber M3 subgun was formally adopted quickly in December, 1942, and was a startling departure from the Thompsons. It cost the government about $20.00 in 1943 dollars. Its receiver was crafted into a tube shape from stamped and welded heavy gauge sheet steel. The trigger and retractor housings were likewise made from sheet steel. The 8-inch barrel was screwed into the front of the receiver. The heavy steel bolt was backed by twin recoil springs, and the firing pin was nothing more than a projection machined into the face of the bolt. The gun was a straight blowback design made to fire from an open bolt. Pulling the trigger released the bolt to jump forward, stripping a round from the magazine, chambering it, and firing it as it slammed home. Firing in full automatic mode only, the gun would continue to fire as long as the trigger was depressed and there were cartridges in the magazine. The sear would hold the bolt to the rear when the trigger was released unless the ammo in the magazine was exhausted, at which point the bolt would be in the forward position. The bolt could be retracted manually by a prominent spring-loaded lever assembly on the right side of the receiver. A spring-equipped ejection port cover was employed, and when placed down over the ejection port, it served as a safety. The sights were fixed; the rear sight was a simple stamping with an aperture in it. A retractable heavy wire shoulder stock was employed.
While the gun was chambered for the .45 ACP cartridge, it could be easily converted to 9mm with the use of a magazine adapter and changing out the bolt and barrel with 9mm versions. The M3 fed from a 30-round double-column single-feed magazine, mimicking the type used on the Stens. These were not quite as reliable as the double-position feed of the Thompsons, which required less energy to strip a round into the chamber. The rate of fire was a comparatively slow 350 – 450 rounds per minute, compared to some models of the Thompson, which could push to 725 RPM. With its slower cyclic rate, the M3’s trigger could be “tapped off” for single shots if needed. The gun weighed 8.15 pounds, compared to the Thompsons, which weighed from 10.45 to 10.75 pounds, depending on the model. Overall length with the stock extended was 29.8 inches, and when pushed forward, the total length was a handy 22.8 inches, making it very suitable for tank, engineer and aviation crews. The gun could be slung using the standard M1 carbine canvas sling.
The M3 was used throughout World War II, supplementing the more prevalent Thompsons which remained the standard SMGs. The “grease gun” was generally satisfactory but it had one main design flaw. The retracting lever mechanism was both complex and somewhat fragile, resulting in some unfortunate failures in combat. The solution to the problem in December, 1944 was both simple and ingenious. In the newer M3A1, the retracting lever was dispensed with entirely, replaced by a single finger hole for the right forefinger in the bolt, accessible through a larger ejection port. Inserting a finger into this hole allowed the user to retract the bolt back so it could be caught by the sear. Another nice touch for the newer gun was that the bolt and recoil springs could be removed for cleaning from the front by simply unscrewing and removing the barrel. The older M3 required removing the retractor housing from the upper receiver for this. Additional changes were a stock plate and magazine filler being added to the wire stock, and an oil can incorporated into the pistol grip. A longer barrel ratchet spring was used for more positive retention of the barrel, and the magazine catch was provided with a guard to help prevent inadvertent release of the magazine. Weight of the M3A1 was a reduced 7.95 pounds. The gun illustrated for this article is one of the original WWII M3s. The M3A1 saw little (if any) combat action during WWII, but was used extensively in Korea and Vietnam.
The Guide Lamp division of General Motors made approximately 646,000 M3s and M3A1s from 1943 to 1945 during WWII. A version of the M3 that incorporated a sound suppressor in the barrel was developed, with about 1,000 being produced during the war for the OSS (Office of Strategic Services), the forerunner to the present day CIA. After the war, a curved barrel was developed for clearing tanks and transport vehicles from the inside and for shooting around corners. A cone-shaped flash hider was also developed, suitable for both the M3 and the M3A1. About 33,200 M3A1s were produced by the Ithaca Gun Company of Ithaca, New York during the Korean War to supplant those guns left over from the WWII era.
M3s and M3A1s, sometimes produced outside the U.S., have been used by 18 other nations at one time or another. M3A1 submachine guns continued to see some use by our armed forces into the late 1980s, and as late as the Gulf War were still in inventory with engineer units attached to the 1st Armored Division. Originally designed to be cheaply made and thrown away when worn out, they were a surprising mainstay component of our combat forces for many years. Collectors of Class III (legal full-auto firearms) treasure them. Such collectors should be prepared to part with thousands of dollars, endure federal paperwork, and purchase a federal tax stamp. All this to own a gun that originally cost about $20.00! Some semiautomatic look-alikes with longer legal 16.5-inch barrels have been made for those without the inclination and/or funds to purchase the originals. Some semiautos in “pistol” form with no stocks have been made with 8-inch barrels. The originals occupy a milestone position in historic U.S. small arms weaponry, and are indeed classics.
(c) 2016 JLM
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