By Frank Iannamico

The M3 submachine gun design had begun as the T-15 prototype, which was developed by the Ordnance Department and the Inland Division of General Motors. The three key individuals who shared much of the responsibility of the project were: Frederick Sampson, Chief Engineer of the Inland Division of General Motors; George Hyde, who had a number of original submachine gun and light-rifle designs to his credit; and U.S. Army Ordnance R&D officer Colonel René Studler. No submachine gun requiring extensive machining operations would be considered for adoption. The requirements called for an all metal weapon fabricated from sheet metal stampings to permit fast and inexpensive production with a minimum of machining operations, and no critical metals, such as aluminum, were to be used.

The original T-15 specifications of October 8, 1942, OCM 19007 were altered to include a kit to enable the weapon to be converted from its original .45 caliber to 9mm which was the standard pistol and submachine gun cartridge of the British and the Germans. Another amendment to the original T-15 design was the elimination of the semiautomatic function. This was done to simplify the design. The cyclic rate was such that semiautomatic fire could be accomplished by trigger manipulation. The new designation for the new 9mm/.45 full-automatic-only weapon was the T-20. Five prototype models of the T-20 and five 9mm conversion kits were built by General Motors for testing. The cyclic rate was relatively slow at 400 rounds per minute. There was very little muzzle climb. In the standard test of firing at a 6ft x 6ft target at 50 yards, the T-20 scored 97 hits out of a possible 100. This was a higher percentage than achieved by any other weapon tested in the trials except the Hyde-Inland M2.

U.S. Submachine Gun, Caliber .45, M3

The M3 submachine guns were all metal, fabricated mainly of stamped steel parts to take advantage of speed and economy of manufacture and assembly. Its weight distribution, along with its slow 350-400 rounds per minute cyclic rate, allow for excellent accuracy for a weapon of this type, regardless if the weapon is fired as a pistol with the stock retracted or as a carbine with the stock extended. Control of the weapon when firing bursts is enhanced by the stock being in direct axis with the bore of the barrel assembly. The internal parts were fully enclosed to protect them against any dirt, water or mud. The rear sight, barrel bushing, sear pin bushings, hinge assembly and sling loops were all welded in place. Dual guide rods and springs were employed to provide support and control for the heavy bolt without touching the inside walls of the receiver. The bolt/rod/spring assembly was easily removed from the receiver as a complete unit.

Soldiers’ initial reaction to the M3 was generally negative, mainly because of the weapon’s appearance. The slow cyclic rate also was disliked by troops, who equated effectiveness of a weapon by its cyclic rate. Many epithets were immediately bestowed on the M3; the name that stuck was the “grease gun” because it resembled a tool for lubricating automobiles. After being in service for a few months, the M3 began to gain some respect, but it would never achieve the status of the Thompson submachine gun.

The Guide Lamp Division of General Motors Corporation

General Motors’ Guide Lamp Division was a peacetime manufacturer of automobile lamps, headlight buckets, hubcaps and bumper guards. The Guide Lamp production plant was located in Anderson, Indiana. Guide Lamp had a lot of expertise and experience in sheet metal stampings and was an excellent choice for the manufacturing of the M3 submachine gun.

By June 1944, 1,000 M3s were being manufactured every 24 hours. The initial Guide Lamp contract price for the M3 was $17.92 per unit less the bolt assembly. The initial price was later amended to $18.36 per unit to cover the cost of minor production changes and the packing and shipping of the completed units. The M3 bolt assembly manufacture was subcontracted to the Buffalo Arms Company at a cost of $2.58 per piece. The bolts were then shipped to Guide Lamp for assembly. The total cost of the M3 was nearly one-half the price of the least expensive M1A1 model Thompson. More importantly, the time for producing each weapon was cut in half thus allowing production to keep pace with the growing war-time demand. The M3 was made almost entirely from simple .060 inch-thick sheet metal stampings. The only major parts requiring any machining were the barrel and bolt. The receiver was made from two die-stamped sheet metal halves. The two pieces were then welded together to form the receiver.

The M3 barrel was manufactured by cold swaging, a process that saved a lot of production hours. A steel 40-inch tube for the barrel would first be reamed to the correct inside diameter. The rifling would then be pressed into the barrel by inserting a mandrel and compressing the tube as it is forced through the die. The long piece of tubing would then be cut in sections to produce five M3 barrels. By May 1943 the first M3 submachine guns were rolling off the assembly lines at Guide Lamp. A patent for the M3 firearm construction was filed on May 1, 1944. The inventors listed were Frederick W. Sampson and George J. Hyde. Patent number 2,403,306 was granted.

The first serviceability problems with the M3 were reported by troops undergoing training in the United States during February 1944. The complaint was that the bolt cocking handle assemblies were failing. A closer look at the problem revealed that the retracting pawl on the cocking handle was cracking adjacent to the rivet hole where the pawl was riveted to the brace. An investigation revealed that the metal that was being used in the manufacture of the parts was not well-suited to the heat-treating process. Immediately the correct metal was substituted for the parts involved, and the width of the metal at the rivet hole was increased. Armorers in the field upgraded all M3s in service with the new parts.

The U.S. M3A1 Submachine Gun

The M3 was thought to be as simple and reliable as possible; however, the Ordnance Department felt that the weapon could be simplified even further. A study was conducted to determine if it were possible to eliminate the cocking handle assembly that was the source of most problems and complaints. A way to simplify field stripping and maintenance was also under study.

During the development stages of the M3(E1) submachine gun, the following Ordnance Department rejections, changes and additions were made:

• Eliminate the complete cocking assembly handle and associated parts by the redesign of the bolt.
• The modification requires enlargement of the ejection port.
• A new hinge and a stronger cover spring riveted to the receiver and a redesigned cover plate with improved safety locks.
• Incorporate an ejector slot cut in the full length of the bolt as well as a redesigned guide rod retaining plate to permit removal of the bolt assembly without removing the ejector housing.
• Design the stock to permit its use as a magazine loading tool, eliminating the need for a separate item for that purpose.
• Drill and tap the forward ends of the stock to accommodate a bore cleaning brush.
• Incorporate a larger oiler in the pistol grip.
• Modify the barrel nut to allow its removal using the wire stock as a tool.

Six pilot models incorporating the above modifications were designated as the M3E1 submachine gun. On December 21, 1944, the M3E1 Submachine Gun was approved and officially adopted as: Submachine Gun, Caliber .45 M3A1, thus reclassifying the M3 as Limited Standard.

The total submachine guns manufactured from 1943 to 1945 by Guide Lamp: 606,694 M3s and 82,281 M3A1 models, for a total of 688,975 weapons. The entire World War II production of the M3 and the M3A1 would total only a little more than one-third of the Thompsons produced during the war.

The M3A1 remained the Standard submachine gun of the U.S. Army until the adoption of the M14 in 1957. The M3A1 submachine gun then was relegated to Substitute Standard. The M14 rifle was, in theory, replacing the M1 rifle, the carbine and the submachine gun.

More Firepower!

During World War II, the primary U.S. weapons were the .30 caliber M1 rifle, the .30 caliber M1 carbine and the .45 caliber submachine gun. The M1 rifle was semiautomatic and had a magazine capacity of 8 rounds; it was an accurate weapon designed for long-range targets. The semiautomatic M1 carbine used a less powerful .30 caliber cartridge than the rifle and was a short-range weapon primarily intended to replace hand guns. The submachine gun had a full-automatic function and a magazine capacity of 30 rounds, but its range was limited.

What was needed was a weapon in between the long-range battle rifle and the short-range submachine gun. This was demonstrated by the Germans when information was received to the effect they were fielding a select-fire weapon, the MP43, using a 7.92mm Kurz (short) mid-range cartridge.

As the pace of the war accelerated, U.S. troops encountered new types of terrain and new enemy tactics; the need for more firepower was anticipated.

The T29 Submachine Gun

Inspired by the German MP43, during fall 1944, it appeared advisable to investigate the possibility of modifying the M3 submachine gun to permit the firing of the carbine cartridge caliber .30 M1. This investigation was entered into in view of the many reports received from the field requesting the development of the submachine gun which would fire the caliber .30 carbine round. Considerable study was given by personnel of the design section of the Guide Lamp Division of the General Motors Corporation that was manufacturing the M3 submachine gun.

To reconfigure the M3 submachine gun to accomplish the above, it was necessary to use a spring-loaded ejector to soften up ejection. To facilitate retracting the bolt, and still maintain the proper spring load to prevent the bolt from striking the rear receiver in recoil, it was necessary to employ both a shorter, stronger spring and a longer, low-rate spring; the short spring being required primarily to stop the bolt in recoil and the long spring to feed and fire the cartridge. A 30-round magazine was made by attaching two 15-round M1 carbine magazines together; the magazine well was enlarged to accept carbine magazines. A 14-inch long barrel was used to maximize velocity and reduce muzzle flash. The bolt was redesigned for the .30 carbine round.

The .30 caliber T29 weapons were tested during the fall of 1944. The modified submachine guns incorporated the basic design characteristics of the M3A1 submachine gun were completed, and function fired 1500 rounds per weapon. There were many functioning problems encountered due to the more powerful cartridge. Despite the longer barrel, the report and flash were quite excessive. Further study of the T29 submachine gun showed the Type A spring-loaded ejector and the feed ramp would require further development. However, in that the select-fire caliber .30 M2 carbine was standardized in September 1944, it was not deemed advisable to continue further development work on the T29 submachine gun concept, and the T29 project was terminated on November 16, 1944.

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Excerpted in part from the book The M3-M3A1 Submachine Gun, available from Chipotle Publishing LLC.

Special thanks to Curator Alex MacKenzie and the entire staff at the Springfield Armory National Historic Site.
Springfield Armory National Historic Site
Springfield, MA
413-271-3976
www.nps.gov/spar

During a recent visit to the Springfield Armory National Historic Site Museum in Springfield, Massachusetts, Small Arms Review was granted access to the area of the museum where weapons not on display are stored. Only 16-percent of the museum’s collection is currently on exhibit.

One might wonder why some of the more unique, one-off firearms are not on display. I have asked this question of several museum curators over the years, and the answer is always the same. The average military museum visitor is interested in seeing a rifle or handgun that was issued to them, their father or grandfather. Most are not interested in one-of-a-kind prototypes.

High Standard T48 7.62mm FN FAL Rifle Serial Number HS-1

One of the rarest FN FAL rifles was manufactured by the High Standard Corporation, Hamden, Connecticut in 1954. The Belgian FN FAL rifle, as originally manufactured in Europe, was produced using the metric system of measurement. Canada, Great Britain and the United States all used the Imperial system of inches. Any rifle produced in these countries would need to adhere to their standard of measurement. One of the obstacles encountered with the Belgian rifle was that all the factory drawings were done using the metric system.

The Springfield Armory was busy with the T44E4 rifles and numerous other projects and decided to turn the task over to a commercial entity. Bids were taken for the project, and the contract was eventually awarded to the High Standard Corporation. As part of the agreement, High Standard was to manufacture at least 12 functional FN FAL T48 rifles from their final drawings. Harrington and Richardson received a contract and manufactured 510 inch-pattern T48 rifles for testing and evaluation.

Inland M1 Carbine Serial Number 1

The M1 carbine was manufactured during World War II, issued to primarily arm personnel who were not engaged in front-line infantry fighting. The carbine used a new 7.62x33mm cartridge with a 110-grain bullet at a muzzle velocity at approximately 1,970 feet per second. The carbine was designed to supply a more effective weapon to those who would normally be issued a handgun. The M1 carbine was manufactured by a large number of contractors. One of those contractors was the Inland Division of General Motors. In the museum’s holdings is the first production M1 carbine made by Inland, serial number 1, with two unusual characteristics: a “web” forward of the trigger guard and a corrugated curved butt plate. The first five tool room models of the Inland carbine were made by R.F. Sedley, Inc., Philadelphia, PA.

T29 .30 Caliber Grease Gun Serial Number X38

The experimental T29 submachine gun was developed by the Guide Lamp Division of General Motors during the fall of 1944. The T29 is a straight blowback M3A1 “Grease Gun” chambered for the .30 carbine cartridge. The barrel is 14 inches in length; the overall length is 28.8 inches. Development was terminated with the introduction of the select-fire M2 carbine.

Savage Submachine Gun .45ACP Serial Number X-1

The experimental Savage submachine gun, caliber .45, was manufactured by Savage Arms, Utica, New York. Equipped with a folding spike bayonet, magazine and sling, this submachine gun shares many features with the production Reising M50 submachine gun and feeds from a 20-round Reising magazine. The weapon was designed in the 1940s by Eugene Reising for Savage Arms.

High Standard Submachine Gun .45 ACP Serial Number 7

The High-Standard Submachine Gun Caliber .45 was designed by Carl G. Swebilius of High Standard with the patents assigned to the corporation. The .45 caliber prototypes were made by High Standard; production UD42 9mm models were manufactured by Marlin for the United Defense Supply Corporation. Reportedly only seven weapons in caliber .45 ACP were made for submission to various testing boards.

Submachine Gun Thompson M1A1 .45 ACP Serial Number 1244194

Manufactured by Savage for the Auto-Ordnance Corporation, Bridgeport, Connecticut, this is a presentation M1A1 Thompson submachine gun with a polished blue finish. The serial number represents the total number of Thompson submachine guns; 1928, M1 and M1A1 models made by Savage. The weapon was donated to the Springfield Armory NHS by Savage Arms, Westfield, Massachusetts on October 17, 1978.

Swedish-K, 9mm Caseless Ammunition Serial Number 356615

A submachine gun that was introduced to the Navy SEALs at Fort Bragg and remained in their inventory through the Vietnam War, was the Swedish Model 45, also known as the m/45 or Swedish-K.

A Swedish-K submachine gun, serial number 356615, was converted by the U.S. Smith & Wesson Corporation to electrically fire caseless 9mm ammunition. The m/45 was followed by several S&W Model 76 submachine guns that were designed for caseless ammunition before the program was terminated.

Smith & Wesson Model 76, Caseless Ammunition Serial Number X219

Model 76 serial number X219 was one of several Model 76 submachine guns converted to fire caseless ammunition. The ammunition was fired electrically. Power was supplied by a 30-volt dry cell battery located in a compartment forward of the trigger guard. The magazine release lever was redesigned to clear the battery box. Note the on-off safety switch on the pistol grip (barrel is missing from the weapon).

U.S. Rifle, M1 Caliber .30 Serial Number 1

Manufactured by Springfield Armory, Springfield, Massachusetts in May 1934, this is the first model shop semi-automatic, gas-operated (gas-trap) M1 Garand rifle with 8-round clip feed mechanism. Manufactured by semi-production, tool room methods in the Model Shop at Springfield Armory under direct supervision of John Garand. The cost to the government for the 80-model shop M1 rifles was $1,831.00 in 1934, or $32,268.51 in 2018 dollars.

U.S. Rifle, M1 Caliber .30 Serial Number 81

This M1 was manufactured by Springfield Armory, Springfield, Massachusetts in 1937. It is the first series production model M1 gas-operated, semi-automatic rifle with 8-round clip feed mechanism. Parkerized finish with many small parts blued. This is the first production line M1 manufactured in 1937 at a cost of $214.54. Serial numbers 1 to 80 were tool room models.

U.S. Rifle, T20 Caliber .30 Serial Number 1

The T20 was manufactured at Springfield Armory, Springfield, Massachusetts in October 1944. Experimental gas-operated, select-fire rifle, essentially a modified M1 adapted to a 20-round detachable BAR box magazine. The receiver was made .3125-inch longer than a production M1 to solve a problem feeding from the BAR magazine. The weapon was designed to fire from open bolt in the full-auto mode; closed bolt in semi-auto mode. The open bolt feature did not adequately solve cook-off problems.

Muzzle velocity was 2750 feet per second and cyclic rate of fire 500rpm. Weapon has an overall length of 44.5 inches, a barrel length of 24 inches and weighs approximately 10 pounds without accessories. Development of the T20 model was terminated in January 1945 with recommendations that minor changes and strengthening of various components be made. A rifle incorporating these minor design changes was designated as the T20E1.

Remington T22E2 .30 Serial Number 1

Concurrent with Garand’s work on the T20 rifle, a competitive contract was awarded to Remington Arms Company to develop an improved M1 rifle. Remington’s prototypes were designed around a standard length M1 receiver. Like the T20, the T22 used a BAR-style 20-round magazine. Manufactured and developed by Remington Arms, Ilion, New York. The T22E2 was essentially an M1 converted to select fire and modified for a detachable box magazine.

Belt-Fed German Fallschirmjagergewehr, FG42

After World War II ended, the idea to develop a new U.S. general purpose, light machine gun was renewed. A captured World War II German weapon, a late model FG42, was examined and adopted as a base design. The FG42 (Fallschirmjagergewehr, or Paratroopers Rifle) was a limited production, shoulder-fired, rifle caliber weapon intended solely for the German paratroop forces, produced from stampings and welding.

The mechanical solution for the conversion was engineered by the Bridge Tool & Die Works, Philadelphia, Pennsylvania, in 1946. The resulting weapon is a conversion of the Type 2 FG42 German paratrooper rifle with the belt feeding mechanism of the Maschinengewehr 42, a German, belt-fed general purpose machine gun, fabricated from sheet metal stampings. The Bridge Tool & Die conversion weapon is a gas-operated, blowback type combination—air-cooled; bipod supported; with forward handgrip and rear shoulder stock. The receiver cover is marked WaA 147.

T33 Clarke Arms Rifle Serial Number 8

The Clarke Arms Company of Boston entered their T33 series rifles in the U.S. Ordnance Department’s lightweight rifle competition. The T33 rifle development program was begun in March 1949. The weapon was a lightweight, selective full- and semi-automatic rifle. The purpose of the lightweight rifle program was to replace the M1 rifle. This project was suspended in late 1950, because the weapon lacked sufficient ruggedness and demonstrated poor performance under adverse conditions. The Clarke Arms Company dissolved on December 22, 1954.

T44 Rifle Serial Number 1

The first 7.62mm T44 rifles were built on .30 caliber T20 receivers. Spacers were used in the receiver to adapt the T20 receiver for the shorter 7.62mm cartridges. A new short receiver, specifically designed for the 7.62mm round, was introduced on the T44E4 model.

First Production M14 Rifle Serial Number 2000

The first U.S. M14 rifle off the series production line at the Springfield Armory in 1957 was serial number 2000. The presentation grade rifle was finished in a high polish blue with a fine black walnut wood stock.

M14E2/A1 Rifle Prototype, Springfield Armory M14 Serial Number 6488

The M14 rifle as issued, was very difficult to fire accurately in full-automatic. As a result, many were issued with selector locks, limiting their operation to semi-automatic-only. In attempt to design an M14 that could effectively use its full-auto feature, the USAIB/M14 was conceived at Fort Benning, Georgia, by Captain Durward D. Gosney. The Springfield Armory M14 Serial Number 6488 was fitted with an in-line pistol grip stock, wooden foregrip, muzzle stabilizer and commercial rubber recoil pad. In this configuration, the M14 demonstrated that the automatic fire accuracy requirements could be consistently achieved.

Due to size limitations, only a small portion of the unique firearms stored at the Springfield Armory Museum are featured in this article, as are the brief descriptions. Watch future issues of Small Arms Review for more in-depth articles and photos on many of these weapons.

Special thanks to Curator Alex MacKenzie and the entire museum staff.

For more information about the museum:

Springfield Armory National Historic Site
One Armory Square, Suite 2
Springfield, MA 01105-1299
Phone: 413-271-3976 Website: nps.gov/spar

After the overthrow of the Qing Dynasty, Chinese leader Sun Yat Sen confirmed the Republic of China on 10 October 1911 and China then embarked on 40-plus years of internal struggle and war. During the 1920s China was embroiled in a civil war between the Chinese Communist forces led by Mao Tse-tung and the Chinese Nationalist Party (Kuomintang) led by Chiang Kai-shek, who took control of the Kuomintang Party and the army during 1926. With China embroiled in a bitter civil war, Japan saw the opportunity to advance on Manchuria in northeast China during 1931. Manchuria was easily taken and occupied by the Japanese until the end of World War II. The Japanese attacked again on 7 July 1937, troops poured into China, attempting to occupy the five Western provinces. Chiang Kai Shek was caught between fighting the Communist Chinese and the Japanese; he focused on defeating his Chinese rivals.

During World War II, the United States became allied with the Chinese Nationalists and provided massive military aid through the United States’ Lend Lease Program to assist China in defeating the Japanese. The Chinese were supplied with large amounts of U.S. small arms. The wartime plan of the U.S. was to assist China in becoming a strong ally and a stabilizing force in Asia after the war. When World War II ended the Chinese civil war intensified, eventually resulting in a Communist victory in 1949. The Nationalist government left the mainland and settled on the island of Formosa (Taiwan) located off of the southeast coast of the mainland. Communist leader Mao Tse-tung renamed mainland China the Peoples Republic of China.

The Chinese Type 36 Submachine Gun

After the end of World War II and the U.S. Lend Lease Programs, the Chinese began to copy and manufacture weapons of both Soviet and U.S. designs. One of the U.S. weapons they copied was the U.S. M3A1 submachine gun, commonly known by its nickname “Grease Gun.” The M3 and the product-improved M3A1 were first designed and fielded by the United States during World War II. The first Chinese M3A1 clone produced on mainland China was adopted in 1947 and thus designated as the Type 36. The designation came from the Chinese Republic calendar year that started in 1911 when the Republic of China was established by Sun Yat Sen. The Chinese .45 caliber Type 36, manufactured at the Shenyang 90th Arsenal, near Mukden, China was a near exact copy of the U.S. made M3A1, except for the Chinese markings on the magazine housing. Reportedly fewer than 10,000 Type 36 submachine guns were produced before Communist forces overran the factory.

The Chinese Type 37 Submachine Gun

Like the Chinese Type 36, the Type 37 was a very close copy of the U.S. M3A1 submachine gun, except the Type 37 was chambered for the 9mm Parabellum cartridge. The Type 37 was manufactured at Mainland China’s 60th Jin Ling Arsenal located in the city of Nanking, China, then the capital city of the Nationalist Chinese. The Type 37 designation of the weapon indicates that it was adopted and manufactured during 1948.

The 9mm Type 37 submachine gun differed only slightly from the Type 36, and was basically a conversion of the .45 caliber Type 36 model. To facilitate the 9mm cartridge, the barrel was extended 8mm further out of the rear of the barrel nut than a standard .45 caliber barrel. This was necessary to reliably feed the shorter 9mm round into the barrel’s chamber. The rear of the 9mm barrel is slightly larger near the receiver end where it is pressed into the muzzle nut. The bolt is similar to the .45 model, except the bolt face was recessed 8mm further to compensate for the portion of the barrel protruding rearward. To feed the Type 37, a copy of the British Sten magazine was used. To permit the 9mm magazine to fit into the magazine well a three-sided magazine adapter was fabricated from a piece of .030 of an inch thick spring steel. The adapter was held in place by two metal tangs on each side. The standard M3A1 magazine release was used. To remove the 9mm magazine adapter the release button must be removed. The adapter is identical to that used in the World War II U.S. 9mm Grease Gun conversion kit, except there are no caliber or drawing numbers present.

The Type 37 was only manufactured for a brief period before the Communists overran the city of Nanking during April of 1949. Prior to the Communist takeover of the Arsenal, the Nationalist Chinese fled to Formosa taking most of the manufacturing equipment with them. Once settled on Formosa, production of the 9mm Type 37 resumed and redesignated as the Type 39. The submachine guns manufactured on Formosa are marked with the logo of the new ordnance department established there, the Combined Service Forces.

Brief History of the M3 and M3A1 Grease Gun

As early as 1939 the United States Ordnance Department had set a number of requirements for a new weapon to replace the expensive Thompson submachine gun.

U.S. Submachine Gun, Caliber 45, M2

There were extensive trials held at Aberdeen Proving Ground in Maryland to test and evaluate foreign and domestic submachine gun designs, which could meet or exceed the Ordnance Department’s requirements. One of the George Hyde designs was considered for adoption early in 1942 as a substitute standard to begin replacement of the Thompson submachine gun. The weapon was selected as a direct result of testing at Aberdeen and was one of several designs submitted by Mr. Hyde. Several prototypes were tested before a final model successfully passed the service test. In April of 1942 the United States adopted the weapon as the U.S. Submachine Gun, Caliber .45, M2. The Marlin Firearms Company was chosen to manufacture the M2.

There were many problems encountered with the production of the M2, and there were still some flaws in the basic design. Several of the M2’s internal parts were designed to be manufactured by powder metallurgy technology and a difficult time with the manufacturing process was encountered partially because of the aforementioned process. The technology was not advanced enough at the time to successfully utilize the method. The parts then had to be redesigned for machining from steel bar stock and this added substantial man-hours to the M2 production time.

While solving problems with the M2 submachine gun were being addressed, the prototype T-20 (M3) submachine gun was tested and evaluated; the weapon had all of the characteristics that the Ordnance Department was looking for. In an Ordnance Committee meeting held in November 1942 it was reported that, “The development of a caliber .45 submachine gun and a 9mm submachine gun: The requirements for these two weapons have been met by the development of a caliber .45 machine pistol which can be converted to 9mm operation by changing the barrel and bolt.”

The T-15 and T-20 Submachine Guns

The select-fire T15 was the prototype of what would become the M3 submachine gun. Like the M2 submachine gun it was designed by George Hyde. The T15 weapon used no critical metals and required a minimum of time-consuming machining. Except for the barrel and bolt assembly the entire weapon was constructed from simple sheet metal stampings. The bolt was designed to ride on two steel rods that were secured by two holes stamped into the rear of the receiver. The rod and bolt assembly was held in place by the barrel that simply was screwed into the front of the receiver. The bolt would slide on the two steel rods never contacting the inside of the receiver. This kept the moving parts impervious to dirt, making it an extremely reliable design. As the project progressed, there were a few changes. One was a lower cyclic rate, and a full automatic only operation. The new prototype weapon was designated the T-20.

The U.S. M3 Submachine Gun

U.S. Army Ordnance R&D officer Réne Studler recruited General Motors to assist with the T-20 development. Fredrick Sampson, chief engineer of GM’s Inland Division was assigned to the project. After a brief, but thorough evaluation of the T20 prototypes, the T20 was officially adopted as the U.S. Submachine Gun, Caliber .45, M3. The M3 – T20 prototype had an overall score of 95 out of a possible 100 in the Aberdeen test, higher than any previous weapon tested. The time period between the conception and production of the M3 submachine gun was an unprecedented seven months. The project was authorized in October 1942 with five working prototypes available for testing by November 1942, and the M3 was adopted by the United States Army on Christmas Eve 1942. The M2 submachine gun contract was canceled when the M3 submachine gun went into production. The initial cost of the M3 was $17.93 per unit, minus the bolt assembly. The contract for the M3 bolts was awarded to the Buffalo Arms Company at a cost of $2.58 per piece.

The U.S. M3A1 Submachine Gun

After the M3 was in service for a period of time the Ordnance Department felt that most of the problems with the weapon design had surfaced and they set requirements for improving the initial design. One of the biggest problem areas with the M3 was with the cocking handle and its related parts. A new bolt was designed that was cocked by the finger of the operator, eliminating the need for a cocking handle. An enlarged ejection port was also needed to incorporate the new style bolt. The new model was standardized as the M3A1 December 1944 and the M3 was then classified as substitute standard. Other improvements and changes incorporated in the M3A1 were: A larger oil container that was contained inside the pistol grip, a new stock design that served as a cleaning rod and a magazine loading tool. The stock could also be used as a wrench to remove a tight barrel, a new barrel nut that had “flats” machined on it so a wrench (or the stock) could be used to easily remove it. The rear guide rod retainer was redesigned so it would clear the ejector, allowing the bolt assembly to be removed from the receiver without removing the ejector housing. Guide Lamp production ceased in August 1945, after manufacturing 606,694 M3 and 82,281 M3A1 submachine guns. An additional 33,227 M3A1 models were manufactured by Ithaca in 1955-1956. The Ithaca M3A1 was nearly identical to the World War II M3A1 weapons manufactured by Guide Lamp. The M3A1 remained the standard U.S. submachine gun until 1957. In addition to China, the M3A1 design was copied and manufactured in Argentina as the P.A.M. 1.

(Special thanks to The United States Marine Corps National Museum, Triangle, Virginia, Mr. Al Houde, Arms Curator, United States Marine Corps National Museum, Quantico, VA, and Mr. Dolf Goldsmith, Texas. The Type 37 submachine gun photographed for this article courtesy of the United States Marine Corps National Museum, Triangle, VA.)

Just a short while later the Germans simplified their original design of the MP38, by utilizing sheet-metal stampings, welded and pressed together. The result was a weapon that could be produced very inexpensively, but more importantly during a major war, manufactured in a short period of time. The new sheet-metal machinegun was called the MP40 maschinenpistole. Despite the fact that the weapon was made of inexpensive materials and methods it was just as reliable as the weapons that were produced from more traditional techniques. While fighting the Germans in North Africa in 1942, the American Army captured a number of MP40 weapons. These were promptly shipped to the Aberdeen Proving Ground in Maryland for evaluation and testing. The Ordnance personnel at Aberdeen were quite impressed with the methods and materials used to make the rugged German submachine gun.

The standard United States submachine gun issued during most of World War Two was the Thompson. The first model of the famous “Tommy Gun” that was procured by the U.S. Army was the 1928 model. The 1928 Thompson was of a design conceived over twenty years earlier. Although extremely reliable and rugged, the Thompson was very labor intensive to produce, heavy and expensive. The M1 and M1A1 Thompson was introduced in 1942, although simplified for ease of manufacture, they were still far too time consuming to produce in the numbers needed to supply the United States and her allies. The U.S. Marines were forced to adopt and procure 80,000 .45 caliber Reising submachine guns in 1942, due to the shortage of Thompsons.

The U.S. Ordnance department had started to test both domestic and foreign submachine guns as early as 1939, even as their first orders for the Thompson were being placed. The testing failed to find a suitable replacement for the Thompson. The Ordnance Department decided to develop their own weapon, the T-20.

The United States Army Ordnance Department recruited the General Motors Corporation to assist with the design and development of the T-20. The GM Inland Division’s Chief engineer Fredrick Sampson was assigned to head up the project. After the successful and thorough testing of the T20 prototypes, the T20 was officially adopted as the U.S. Submachine Gun, Caliber .45, M3. The M3 -T20 prototype had an overall score of 95 out of a possible 100 in the standard Aberdeen small arms test, higher than any previous weapon tested.

On 29 January 1943 the Guide Lamp Division of the General Motors Corporation, and the U.S. Ordnance Department completed negotiations of a contract to manufacture the M3 submachine guns. The initial cost was $17.93 per unit, minus the bolt assembly. This cost would be amended several times during the life of the GM Guide Lamp contract. The contract to manufacture the bolts for the M3 was awarded to the Buffalo Arms Company of New York at a cost of $2.58 per piece. Ordnance contracts W-294-ORD-2107 and W-33-ORD-825 for the initial 300,000 units were awarded to Guide from the Cincinnati Ordnance District. The Guide Lamp factory was located in Anderson, Indiana. Guide Lamp was also manufacturing the .45 caliber sheet metal Liberator pistols, and Browning machine gun barrels. At the peak of production Guide was turning out a new M3 submachine gun every 2.4 minutes. A total of 605,694 M3 models would be accepted by the Ordnance Department from 1943 until early in 1944. The simplified M3A1 model was only produced in 1945, 82,281 were built before production ceased at the end of July.

The US .45 caliber M3 submachine gun, was an air-cooled, automatic only, weapon that fired from an open bolt. The weapon’s rate of fire was a somewhat slow 350- 400 rounds per minute. Semi automatic fire could be quite easily achieved by careful manipulation of the trigger. The U.S. troops that were issued the M3 were not immediately impressed by the new weapon, mostly because of its slow cyclic rate. They perceived that the effectiveness of any given weapon was directly related to the amount of rounds it could expend in a short period of time.

Although the cyclic rate was slow and the appearance unorthodox, the M3 was quite a reliable and effective weapon within its design limits. Its toy-like appearance generated several nicknames for the weapon, some not very flattering. The one that stuck was the grease gun, for its similarity in appearance to an auto mechanics tool. The M3 was easily manufactured from two die-stamped halves of sheet metal that were welded together. At first problems were encountered from the heat of the welding process warping the sheet metal receiver, but the problem was soon solved. The barrels were rifled by using the time saving cold swaging method. The bolt assembly was basically the only part requiring any extensive machining. The double feed, single stack magazine capacity was 30 rounds of .45 ACP ball ammunition. A magazine loader was issued to aid in loading the magazines.

After the M3 was in service for a period of time, the Ordnance Department felt that most of the problems with the weapon’s design had surfaced, and they set requirements for improving the initial design. One of the biggest problem areas with the M3 was with the cocking handle and its related parts. This troublesome assembly would be completely eliminated in the improved M3A1 design. A new bolt was designed that was cocked by the finger of the operator. An enlarged ejection port was also needed to incorporate the new style bolt. The design also allowed for much easier field stripping by eliminating the need to remove the ejector housing in order to remove the bolt assembly from the receiver. The new model was standardized as the M3A1 December 1944. The M3 was then classified as Substitute Standard. The M3 and M3A1 were destined to completely replace the Thompson as the standard U.S. submachine gun, but by the time World War Two ended in 1945, not enough had been produced. Production was abruptly terminated in July of 1945 as the war was in its final days.

During the Korean Conflict of 1950 to 1953 the Thompsons and the M3 and M3A1 submachine guns were pulled from storage and sent to fight another war. By the time hostilities in Korea had ended, the U.S. was facing a shortage of submachine guns according to the peacetime requirements. The United States had provided an enormous amount of WWII weapons to South Korea as military aid during the war. In 1955 the Ithaca Gun Company of Ithaca, New York was awarded contract number DA-19-058-ORD-7854 by the Rochester Ordnance District to manufacture 70,000 M3A1 submachine guns. Production was halted after only 33,227 were produced. In the interim the United States had been searching for a new modern service rifle to replace the M1 Garand rifle. As a result of years of testing and evaluation the Ordnance Department adopted the M14 as the standard U.S. Service Rifle of the U.S. Army. The new M14 was to replace the M1 Rifle, M1 Carbine and the .45 caliber submachine gun. Due to a number of problems the first M14 rifles were not issued until 1959.

When the United States sent advisory personnel into Vietnam in the early 1960s, the troops were armed with many weapons from WWII. As the war endured, U.S. personnel were eventually issued M14, M16 and M16A1 rifles. On 11 December 1961, the United States began to supply an enormous amount of military aid to the South Vietnamese Government. Included in the aid were many World War Two small arms including 1919A4 – 1919A6 machine guns, BARs, M1 rifles, M1 – M2 carbines, and M3 – M3A1 submachine guns.

In order to keep the M3 and M3A1 weapons in serviceable condition during the Vietnam War, the production of spare parts was resumed. The Vietnam era parts will be stamped with only the Ordnance drawing number of the part. The letter codes GL indicating Guide Lamp, and the ITG code representing the Ithaca Company are absent. There was one insignificant change introduced during the Vietnam era, and that was the introduction of the chromium-lined barrel. The corrosion resistant chromium bore was implemented because of periods of extreme humidity and rainfall in the country. These barrels are easily recognized by the dull silver appearance of their bores and chambers.

Suppressed or “silencer” equipped versions of the M3 and M3A1 weapons were used by U.S. sniper teams in Vietnam to quietly dispatch any enemy personnel that might compromise their positions. These weapons were fitted with suppressors manufactured by the SIONICS corporation. A few suppressor-equipped grease guns were also used by the enemy in Vietnam. The enemy weapons used a suppressor that was very similar in construction to those made by Bell Laboratories for the Office of Strategic Services (OSS) during WWII. Since the OSS grease gun suppressors had no identifying markings on them, it wasn’t known for certain if the enemy suppressors were refurbished U.S. issue or Chinese copies. There was one internal difference noted. The enemy suppressors used oil soaked felt, original U.S. produced versions ones did not.

(Dan’s Note: There were a number of Special Operations personnel and others who have described taking an M3A1 Greasegun, and replacing the recoil springs with cut down M2HB springs- this increased the cyclic rate to around 800rpm, but was destructive to the rear end of the receiver).

A number of U.S. M3-M3A1 submachine guns were also captured and used against the United States forces and their South Vietnamese allies. The Viet Cong Guerrillas especially favored the compact and easily concealed “grease gun”. Communist China had supplied the Viet Cong and NVA troops with a substantial number of their own indigenously produced version of the M3A1. The Chinese copies of the M3A1 submachine gun were designated as the M36 when chambered for the .45 caliber cartridge and the M37 chambered for 9mm rounds. These two weapons were direct copies of “grease guns” that the United States had supplied to a desperate China during WWII. The weapons were very similar to the U.S. manufactured M3A1model except for the Chinese markings on the magazine housings.

The M3 and M3A1 grease guns are the only U.S. weapons adopted during WWII that continue to serve even today. Some weapons like the famous Thompson Submachine Gun endear, while others like the utilitarian M3-M3A1 grease guns simply endure.

This article was excerpted from the book The M3 and M3A1 Grease Gun. The book is available from Moose Lake Publishing 207-683-2959