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RS Wiki: The Thompson "Tommy Gun" Submachine Gun

Thompson Submachine Gun

Another round for me for copying from Wikipedia. This time, this is about one of the famous classic guns that many of us are familiar with, especially these are much in use in Hollywood Movies that cover the Prohibition Era in the United States, or made infamous by Chicago gangs during that period. For me, I best remember the Tommy Gun in the movie The Untouchables starred in by Kevin Costner and Sean Connery (Directed by Brian de Palma in 1987). Also known as the "Grease Gun" I may have one of these soon, as soon as they have drum (or ­Plate) magazine ready for those CYMA and JG replicas. Plus a Cuban Cigar to chew on, the loadout would look pretty cool... "You can get more with a nice word and a gun than you can with a nice word." (Al Capone).

The Thompson submachine gun is an American submachine gun that became infamous during the Prohibition era. It was a common sight of the time, being used overwhelmingly by both law enforcement officers and criminals. The Thompson was also known as the "Tommy Gun", "Chopper", "Chicago Typewriter" and "Chicago Piano". The Thompson was favored by soldiers and civilians alike for its compactness, large .45 ACP bullet, and high volume of automatic fire.

History and service

The Thompson Submachine Gun was designed by General John T. Thompson, who was inspired by the trench warfare of World War I to develop a "one-man, hand-held machine gun", firing a rifle caliber round. While searching for a way to allow such a weapon to operate safely, Thompson came across a patent issued to John Bell Blish. Thompson found a financial backer, Thomas Fortune Ryan, and started the Auto-Ordnance Corporation in 1916 for the purpose of developing his weapon. The principal designers were Theodore H. Eickhoff, Oscar V. Payne, and George E. Goll. By late 1917, the limits of the Blish lock were discovered, and it had been found that the only cartridge currently in U.S. service suitable for use with the lock was the .45 ACP (Automatic Colt Pistol). The project was then titled "Annihilator I", and by 1918, most of the design issues had been resolved. However, the war ended before prototypes could be shipped to Europe.

At an Auto-Ordnance board meeting in 1919 to discuss the marketing of the "Annihilator", with the war over, the weapon was officially renamed the "Thompson Submachine Gun". While other weapons had been developed shortly prior with similar objectives in mind, the Thompson was the first weapon to be labeled and marketed as a "submachine gun".

The Thompson first entered production as the Model of 1921. It was available to civilians, though its high price resulted in few sales. Model of 1921 Thompsons were first sold in small quantities to the U.S. Post Office (to protect the mail from a spate of robberies), followed by several police departments in the United States and minor international sales to various armies and constabulary forces, chiefly in Central and South America. Thompsons were also acquired by the Irish Republican Army from supporters in the U.S. and were used in the latter stages of the Irish War of Independence and Civil War.

The Thompson achieved most of its early notoriety in the hands of Prohibition and Depression-era gangsters and in Hollywood films. Nationalist China also acquired a quantity for use against Japanese land forces, and eventually began producing copies of the Thompson in small quantities for use by its various armies and militias.

In 1938, the Thompson submachine gun was adopted by the U.S. military, serving during World War II and later into the Korean War, as well as early stages of the Vietnam War. Other Allied countries purchased the Thompson as well, notably the United Kingdom and France. Modifications to simplify production and reduce cost were made in 1942, resulting in the M1 and M1A1 models, which were commonly carried by both non-commissioned and commissioned officers.

There were two military types of Thompson SMG. The M1928A1 used a 20- and later 30-round box magazine, or 50- and 100-round drums. It had cooling fins on the barrel, and its cocking handle was on the top of the receiver. The M1 and M1A1 had a plain barrel without cooling fins, a simplified rear sight, a 20- and later 30-round box magazine, and the cocking handle was on the side of the receiver. The M1928A1 along with the regular M1928 was the choice of the Marines. The M1A1 was the choice of the Army. Thompson intended the weapon as an automatic 'trench-broom' to sweep enemy troops from the trenches, filling a role the BAR had proved incapable of. Ironically, this concept was adopted by German troops using their own submachine guns in concert with sturmtruppen tactics.

The Thompson found particular utility in World War II in the hands of Allied troops as a weapon for scouts, non-commissioned officers, and patrol leaders. In the European theater, the gun was widely utilized in British and Canadian Commando units, as well as U.S. paratroop and Ranger battalions. A Swedish variant of the M1928A1, called Kulsprutepistol m/40 ("Submachine Gun m/40" [Directly translated "Bullet spurt pistol"]), served in the Swedish Army between 1940 and 1951. Through Lend-Lease, the Soviet Union also used the Thompson, but this practice was not widespread.

In the Pacific Theater, Australian Army infantry and other Commonwealth forces initially used the Thompson extensively in jungle patrols and ambushes, where it was prized for its firepower, though its hefty weight and difficulties in supply eventually led to its replacement by other submachine guns such as the Owen and Austen. The U.S. Marines also used the Thompson as a limited-issue weapon, especially during their later island assaults. The Thompson was soon found to have limited effect in heavy jungle cover, where the low-velocity .45 bullet would not penetrate most small-diameter trees, or Japanese helmets or protective vests (in 1923, the Army had rejected the .45 Remington-Thompson, which had twice the energy of the .45ACP). In the U.S. Army, many Pacific War jungle patrols were originally equipped with Thompsons in the early phases of the New Guinea and Guadalcanal campaigns, but soon began employing the BAR in its place, especially at front (point) and rear (tail) positions, as a point defense weapon.

By the time of the Korean War, the Thompson had been withdrawn from service as a standard-issue submachine gun with U.S. forces. It was replaced by the M3/M3A1 submachine gun, and the M1/M2 carbine. Many Thompsons were distributed to Chinese armed forces as military aid before the fall of Chiang Kai-Shek's government to Mao Zedong's Communist forces in 1949. During the Korean War, American troops were surprised to encounter Chinese Communist troops heavily armed with Thompsons, especially during surprise night assaults. The gun's ability to deliver large quantities of short-range automatic assault fire proved very useful in both defense and assault during the early part of the conflict. Many of these weapons were recaptured and placed back into service with American soldiers and Marines for the balance of the war.

The Thompson was also used in limited issue by the U.S. Marine Corps (carrying over from their Post Office service) as the M1928 in a series of interventions in Central America, particularly Nicaragua, where it was popular with the Marines as a point-defense weapon for countering ambush by Sandinista guerrillas.

During the Vietnam War, some South Vietnamese army units and defense militia were armed with Thompson submachine guns, and a few of these weapons were used by reconnaissance units, advisors, and other American troops. It was later replaced by the M16.

The Thompson was also used by U.S. and overseas law enforcement and police forces, most prominently by the FBI. The FBI used Thompsons until 1976, when it was declared obsolete. All Thompsons in U.S. government possession were destroyed, except for a few token museum pieces and training models.

The Thompson, or copies of the gun, are still seen from time to time in modern day conflicts, such as the Bosnian War.

Operating characteristics

The Thompson, especially the early Model 1921, has a fairly high rate of fire at 900+ rounds per minute (rpm), higher than many other submachine guns of smaller caliber. This rate of fire, combined with a rather heavy trigger pull and a stock with excessive drop, increases the tendency of the gun to climb off target in automatic fire. Compared to modern 9mm submachine guns, the .45 Thompson is quite heavy. By the standards of the day the Thompson was one of the most effective and reliable submachine guns available.

Because of its gangster-era and World War II connections, Thompsons are highly sought as collector's items. An original Model 1928 in working condition can easily fetch US$20,000 or more. Semi-automatic versions are currently produced by Auto-Ordnance Company, a division of Kahr Firearms. Approximately 1,700,000 of these weapons were produced by Auto-Ordnance, Savage Arms, and Colt, with 1,387,134 being the simplified World War II M1 and M1A1 variants (without the Blish lock and oiling system).


Persuader and Annihilator

There were two main experimental models of the Thompson. The Persuader was a belt-fed version developed in 1918, and the Annihilator was fed from a 20 or 30-round box magazine, which was an improved model developed in 1918 and 1919. Additionally, the 50- and 100-round drum magazines were developed.

Model of 1919

The Model 1919 was limited to about 40 units, with many variations noted throughout. The weapons had very high cyclic rates around 1,500 rpm. This was the weapon Brigadier General Thompson demonstrated at Camp Perry in 1920. Almost all M1919s were made without buttstocks and front sights, and the final version closely resembled the later Model 1921. The City of New York Police Department was the largest purchaser of the M1919. This model was designed as an automatic Colt .45 to "sweep" trenches with bullets.

  • Caliber: .45ACP (11.4x23mm), .22LR, .32ACP, .38ACP, and 9mmP[14]
  • Weight (empty): 3.75 kilograms (8 lb 4 oz)
  • Length: 808 millimeters (31.8 in)
  • Barrel length: 267 millimeters (10.5 in)
  • Cyclic rate of fire: 1,500 rpm (actual delivered, about 700)
  • Capacity: 20- or 30-round box; 50 or 100-round drum; 18 rounds .45 Peters-Thompson shot cartridges
  • Range: 55 yd (50 meters)


Model of 1921

M1921 was the first major production model. Fifteen thousand were produced by Colt for Auto-Ordnance. In its original design, it was finished more like a sporting weapon, with a blued, finned barrel and vertical foregrip. It is a semi-blowback weapon incorporating the Blish lock. The M1921 was quite expensive to manufacture, with the original retail cost around $225, because of its high quality wood furniture and finely-machined parts. The Model 1921 was famous throughout its career with police and criminals and in motion pictures. The weapon had a relatively high 800+ rpm rate of fire.

Model of 1923

The Model 1923 was introduced to potentially expand the Auto-Ordnance product line and was demonstrated for the U.S. Army. It fired the .45 Remington-Thompson cartridge from a 14-inch (35.5 cm) barrel, with greater range and power than the .45 ACP. It introduced a horizontal forearm, sling, bipod and bayonet lug. The M1923 was intended to fill the role of the Browning Automatic Rifle (BAR), but the Army was satisfied with the BAR and did not give the Model 1923 much consideration, so it was not adopted.

BSA Thompsons

In an attempt to expand interest and sales overseas, Auto-Ordnance partnered with and licensed Birmingham Small Arms Company (BSA) to produce a European model. These were produced in small quantities and have a different appearance than the classic style. BSA Thompsons were produced in calibers such as 7.65mm Parabellum (called .30 Luger in the U.S.) and 9 mm Para, and were tested by various governments, including France in the mid 1920s. The design was never successfully marketed.

Model of 1927

The M1927 was the semi-automatic-only version of the Model 1921. It was made by modifying an existing M1921, including replacing certain parts. The "Thompson Submachine Gun" inscription was machined over to replace it with "Thompson Semi-Automatic Carbine", and the "Model of 1921" inscription was also machined over to replace it with "Model of 1927." Although the Model 1927 was semi-automatic only, it was easily converted to fully automatic by utilizing certain M1921 parts, and is classified as a machine gun under the National Firearms Act of 1934.

Model of 1928

The Model 1928 was the first type widely used by military forces, with the U.S. Navy and U.S. Marine Corps as major buyers through the 1930s. The original M1928s were M1921s with weight added to the actuator, which slowed down the cyclic rate of fire, a U.S. Navy requirement. With the start of World War II, major contracts from Britain and France saved the manufacturer from bankruptcy. This model was standardized as the M1928.


The M1928A1 variant entered mass production before the attack on Pearl Harbor, as on-hand stocks ran out. Changes included a horizontal forend, in place of the distinctive vertical foregrip ("pistol grip"), and a provision for a military sling. Despite new U.S. contracts for Lend-Lease shipments abroad to China, France, and the United Kingdom, as well as the needs of American armed forces, only two factories supplied M1928A1 Thompsons during the early years of World War II. The weapon was mostly used in the U.S. military by the Marine units in the Pacific Theater. Though it could use both the 50-round drum and the 20- or 30-round magazines, active service showed the drums were more prone to jamming and extremely heavy and bulky, especially on long patrols. 562,511 were made.

In addition, the Soviet Union received M1928A1s, included as standard equipment with the M3 light tanks obtained through Lend-Lease. The weapons were never issued to the Red Army, however, because of a lack of .45 ACP ammunition on the Eastern Front, and were simply put in storage. As of September 2006, limited numbers of these weapons have been re-imported from Russia to the United States as disassembled "spare parts kits", the entire weapon less the receiver (as required by Federal law).


The M1, formally adopted as the United States Submachine Gun, Cal. .45, M1, was a result of further simplification. The bolt was modified and rate of fire was also reduced to approximately 600-700 rpm. The M1 utilized a simple blowback operation, the charging handle was moved to the side, and the flip-up adjustable rear sight replaced with a fixed aperture (peep sight). The slots adjoining the magazine well allowing use of the drum magazine were removed, as were the Cutts compensator, the barrel cooling flanges, and the Blish lock.

The less expensive and more-easily manufactured "stick" magazines were used exclusively in this version, with a new 30-round version joining the familiar 20-round type.

The M1 also has a permanently attached buttstock, and was first issued in 1942.


The multi-piece firing pin of the M1 was supplanted by a simplified firing pin machined into the face of the bolt. The 30-round magazine was very common. Reinforcement wings were added to the fixed rear sight.

The M1A1, formally adopted as the United States Submachine Gun, Cal. .45, M1A1, could be produced in half the time of the M1928A1, and at a much lower cost. In 1939, Thompsons cost the government $209 apiece. By the spring of 1942, cost reduction design changes had brought this down to US$70. In February 1944, the M1A1 reached a low price of US$45 each, including accessories and spare parts. By the end of 1944, the M1A1 was replaced with the even lower-cost M3 (commonly called "Grease Gun").

Model 1927A1

The Model 1927A1 is a semi-automatic only version of the Thompson, produced by Auto-Ordnance (West Hurley, New York) for the civilian gun market from 1974 to 1999. It is officially known as the "Thompson Semi-Automatic Carbine, Model of 1927A1." The internal design is completely different and operates from the closed bolt. It has been produced since 1999 by Kahr Arms of Worcester, Massachusetts. This weapon should not be confused with the earlier M1927 produced by Colt for Auto-Ordnance, although its name and designation references the earlier weapon.

Model 1927A3

The Model 1927A3 is a semi-automatic, .22 caliber version of the Thompson produced by Auto-Ordnance in West Hurley.

Model 1927A5

The Model 1927A5 is a semi-automatic, .45ACP version of the Thompson produced by Auto-Ordnance in West Hurley. It featured an aluminum receiver to reduce its weight, since it has no buttstock.

Civilian ownership in the United States

Because of the perceived popularity of submachine guns such as the Thompson with gangsters in the 1920s and 1930s, the United States Congress passed the National Firearms Act in 1934. Among its provisions, all owners of any fully-automatic firearm were required to register them with the predecessor agency of the modern Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF). The law also placed severe restrictions on the possession, transfer and transport of the weapons.

All prospective buyers had to register with the government and pay the $200/item transfer tax. Registration required the prospective buyer to declare a reasonable need for owning the weapon, to supply a citizenship certification, photographs and fingerprints. In addition, a certification from state or local law enforcement or court officers the buyer is not under investigation for a crime and possession of the weapon will not violate state or local law is required. Once the paperwork is submitted to the ATF, the FBI performs a thorough background check. Only after the purchase had been cleared (a process normally taking at least four months), may the new owner take possession of the weapon.

Owners are forbidden to move the gun out of their state of residence without obtaining prior permission from the ATF. The owner is required to keep the weapon within his exclusive control and may not loan it without immediate supervision to anyone. Thompsons, as well as all other kinds of fully automatic weapons, are under a legal ban in at least nine states and the District of Columbia.

There are several U.S. made semi-automatic variants. These are less regulated at the federal level but are still banned in several states because of their resemblance to the fully-automatic version.

Notwithstanding the legality of ownership, hundreds, if not thousands, of these and other weapons of World War II are in the possession of veterans as "bring back" items. With the number of veterans decreasing rapidly, these weapons fall into the possession of the families as illegal weapons, usually unbeknownst to them. Current law does not allow any of these weapons to be registered. Congress is considering an amnesty law which would permit "bring backs" to be registered and thus save these historic and valuable arms.

Many M1928A1s are still retained in the former Soviet Union, and some have recently been demilitarized by cutting the receiver and imported into the U.S. as spare parts kits.