Thompson submachine gun



Jump to: navigation, search The Thompson is an American submachine gun, invented by John T. Thompson in 1919, that became infamous during the Prohibition era. It was a common sight in the media of the time, being used by both law enforcement officers and criminals.[6] The Thompson was also known informally as: the "Tommy Gun", "Trench Broom", "Trench Sweeper", "Chicago Typewriter", "Chicago Piano", "Chicago Style", "Chicago Organ Grinder", and "The Chopper".[7] [8] [9] [10]

The Thompson was favored by soldiers, criminals, police and civilians alike for its ergonomics, compactness, large .45 ACP cartridge, reliability, and high volume of automatic fire. It has since gained popularity among civilian collectors for its historical significance. {| class="toc" id="toc"

Contents
[hide] *1 History and service
 * 1.1 Development
 * 1.2 Early use
 * 1.3 World War II
 * 1.3.1 Magazine developments
 * 1.3.2 M1 development
 * 1.3.3 Usage
 * 1.4 After World War II
 * 2 Collector interest
 * 3 Features
 * 3.1 Operating characteristics
 * 3.2 Disassembly
 * 4 Variants
 * 5 Prototypes
 * 5.1 Persuader and Annihilator
 * 5.2 Model 1919
 * 6 The Thompson in rifle development
 * 6.1 Thompson .30 Carbine
 * 7 Production
 * 7.1 Model 1921
 * 7.2 Model 1923
 * 7.3 Model 1921AC (1926)
 * 7.4 Model 1928
 * 7.5 M1928A1
 * 8 M1 Thompsons
 * 8.1 M1
 * 8.2 M1A1
 * 9 Semi-Automatic
 * 9.1 Model 1927
 * 9.2 Model 1927A1
 * 9.3 Model 1927A3
 * 9.4 Model 1927A5
 * 10 Export variants
 * 10.1 BSA Thompsons
 * 11 RPB Thompsons
 * 11.1 Special purpose variant
 * 11.2 Silenced variant
 * 12 Civilian ownership
 * 12.1 Canada
 * 12.2 United States
 * 13 Users
 * 13.1 Non-state groups
 * 14 See also
 * 15 References
 * 16 External links
 * }

Development
The Thompson Submachine Gun was developed by General John T. Thompson who originally envisioned an auto rifle (semi-automatic rifle) to replace the bolt action service rifles then in use. While searching for a way to allow such a weapon to operate safely without the complexity of a recoil or gas operated mechanism, Thompson came across a patent issued to John Bell Blish in 1915 based on adhesion of inclined metal surfaces under pressure.[11] Thompson found a financial backer, Thomas F. Ryan, and started the Auto-Ordnance Company in 1916 for the purpose of developing his auto rifle. The principal designers were Theodore H. Eickhoff, Oscar V. Payne, and George E. Goll. By late 1917, the limits of the Blish Principle were discovered: rather than working as a locked breech, it functioned as a friction-delayed blowback action. It was found that the only cartridge currently in U.S. service suitable for use with the lock was the .45 ACP round. Thompson then envisioned a "one-man, hand-held machine gun" in .45 ACP as a "trench broom" for use in the on-going trench warfare of World War I. Payne designed the gun itself and its stick and drum magazines. 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.[12]

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".[8] Thompson intended the weapon as an automatic 'trench-broom' to sweep enemy troops from the trenches, filling a role for which the Browning Automatic Rifle (BAR) had been proven ill-suited.[13] Contemporaneously, this concept was developed by German troops using their own Bergmann MP18 submachine guns in concert with sturmtruppen tactics.[14]

Early use
The Thompson first entered production as the M1921. It was available to civilians, though its high price resulted in few sales. (A Thompson with one Type XX 20 shot "stick" magazine was priced at $200.00, at a time when a Ford automobile sold for $400.00.) M1921 Thompsons were sold in small quantities to the United States Postal Inspection Service[15] (to protect the mail from a spate of robberies)[16] and the United States Marine Corps. Federal sales were followed by sales to several police departments in the US and minor international sales to various armies and constabulary forces, chiefly in Central and South America.[16] The Marines used their Thompsons in the Banana Wars and in China. It was popular with the Marines as a point-defense weapon for countering ambush by Nicaraguan guerrillas, and led to the organization of 4 man fire teams with as much firepower as a 9 man rifle squad. The major complaints against the Thompson were its weight, inaccuracy at ranges over 50 yards, and the lack of penetrating power of the .45 ACP pistol cartridge.[17]

Some of the first batches of Thompsons were bought in America by agents of the Irish Republic, notably Harry Boland. The first test of a Thompson in Ireland was performed by West Cork Brigade commander Tom Barry in presence of IRA leader Michael Collins.[18] A total of 653 were purchased, but 495 were seized by US customs authorities in New York in June 1921. The remainder made their way to the Irish Republican Army by way of Liverpool and were used in the last month of the Irish War of Independence (1919–21).[19] After a truce with the British in July 1921, the IRA imported more Thompsons and they were used in the subsequent Irish Civil War (1922–23). They were not found to be very effective in Ireland. In only 32% of actions where it was used did the Thompson cause serious casualties (death or serious injury) to those attacked.<sup class="reference" id="cite_ref-19">[20] Archetypal gangster image of a Thompson in a violin caseThe Thompson achieved most of its early notoriety in the hands of Prohibition and Depression-era gangsters, motorized bandits and the lawmen who pursued them, and in Hollywood films about their exploits, most notably in the St Valentine's Day Massacre. It has been referred to by one researcher as the "gun that made the twenties roar."<sup class="reference" id="cite_ref-NMAH_20-0">[21] <sup class="reference" id="cite_ref-21">[22]

In 1926 the Cutts Compensator (a recoil brake) was offered as an option for the M1921; Thompsons with the compensator were cataloged as No. 21AC at the original price of $200.00, with the plain M1921 designated No. 21A at a reduced price of $175.00.<sup class="reference" id="cite_ref-Frank_Iannamico_2000_22-0">[23]

In 1928 Federal Laboratories took over distribution of the weapon from Thompson's Auto Ordnance Corporation.<sup class="reference" id="cite_ref-ramsour_23-0">[24] The cost at this time was US$225 per weapon, with $5 per 50-round drum and $3 for 20-round magazine.<sup class="reference" id="cite_ref-ramsour_23-1">[24]

Nationalist China acquired a quantity for use against Japanese land forces, and eventually began producing copies of the Thompson in small quantities for use by its armies and militias. In the 1930s, Taiyuan Arsenal produced copies of the Thompson for Yan Xishan, the warlord of Shanxi province.

The Federal Bureau of Investigation first acquired Thompsons in 1933 following the Kansas City Massacre.<sup class="reference" id="cite_ref-ramsour_23-2">[24]

World War II
A British soldier equipped with a Thompson M1928 submachine gun (drum magazine), November 25, 1940German troops in Tunisia with a captured M1928A1 Thompson submachine gun.In 1938, the Thompson submachine gun was adopted by the U.S. military, serving during World War II and beyond.

There were two military types of Thompson SMG. The M1928A1 had provisions for box and drum magazines. It had a Cutts compensator, cooling fins on the barrel, employed a delayed blowback action and its charging handle was on the top of the receiver. The M1 and M1A1 had a barrel without cooling fins, a simplified rear sight, provisions only for box magazines, employed a straight blowback action and the charging handle was on the side of the receiver. Over 1.5 million military Thompson submachine guns were produced during World War II.<sup class="reference" id="cite_ref-24">[25]

Magazine developments
Military users of the M1928A1 had complaints about the "L" fifty round drum magazine; the British Army officially criticised "their excessive weight, the rattling sound they made...." and shipped thousands back to the U.S. in exchange for box magazines. The Thompson had to be cocked, bolt retracted ready to fire, to attach the drum. It attached and detached by sliding sideways which made magazine changes slow and also created difficulty in clearing a cartridge malfunction ("jam"). Reloading an empty drum with cartridges was an involved process.

In contrast, the "XX" twenty round box magazine was light and compact, it tended not to rattle, and could be inserted with the bolt safely closed. It was quickly attached and detached, and was removed downward making clearing jams easier. The box tripped the bolt open lock when empty, facilitating magazine changes. An empty box was easily reloaded with loose rounds. However, users complained it was limited in capacity. In the field, users frequently taped two "XX" magazines together to speed magazine changes.

Two alternatives to the "L" drum and "XX" box magazines were tested December 6, 1941 at Fort Knox: an extended thirty round box magazine and a forty round magazine made by welding two twenty round magazines face to face. Testers considered both superior to either the "XX" box or "L" drum. The thirty round box was approved as standard in December 1941 to replace the "XX" and "L" magazines.<sup class="reference" id="cite_ref-25">[26] (The concept of welding two box magazines face-to-face was carried over with the UD 42submachine gun.) Australian soldiers equipped with Thompson submachine guns at Tobruk, September 8, 1941.====M1 development==== The staff of Savage Arms looked for ways to simplify the M1928A1, producing a prototype in Feb 1942 which was tested at Aberdeen Proving Ground Mar 1942; Army Ordnance approved adoption as the M1 in Apr 1942. M1s were made by Savage Arms and by Auto-Ordnance. M1s were issued with the thirty round box magazine and would accept the earlier twenty round box, but would not accept the drum magazine.<sup class="reference" id="cite_ref-26">[27]

Usage
The Thompson was used in World War II in the hands of Allied troops as a weapon for scouts, non-commissioned officers (corporal, sergeant and higher ranking), and patrol leaders. In the European theater, the gun was widely utilized in British and Canadian Commando units, as well as in the U.S. Army paratrooper and Ranger battalions, where it was issued more frequently than in line infantry units because of its high rate of fire and its stopping power, which made it very effective in the kinds of close combat these special operations troops were expected to undertake. A Swedish variant of the M1928A1, called Kulsprutepistol m/40 (meaning "submachine gun model 40"), served in the Swedish Army between 1940 and 1951. Through Lend-Lease, the Soviet Union also received the Thompson, but due to a shortage of appropriate ammunition in the Soviet Union, usage was not widespread.<sup class="reference" id="cite_ref-27">[28] A Marine fires on a Japanese position using an M1 Thompson submachine gun during an advance on Okinawa in 1945.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 of over 10 pounds 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 protective armor vests. (In 1923, the Army had rejected the .45 Remington-Thompson, which had twice the energy of the .45 ACP).<sup class="reference" id="cite_ref-28">[29] 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 (trail) positions, as a point defense weapon.<sup class="reference" id="cite_ref-29">[30]

The Army introduced the U.S. M3 and M3A1 submachine guns in 1943 with plans to produce the latter in numbers sufficient to cancel future orders for the Thompson, while gradually withdrawing it from first-line service. However, due to unforeseen production delays and requests for modifications, the M3/M3A1 never replaced the Thompson, and purchases continued until February 1944. At the end of World War II, the Thompson, with a total wartime production of over 1.5 million, outnumbered the M3/M3A1 submachine guns in service by nearly three to one.<sup class="reference" id="cite_ref-30">[31]

After World War II
Two Israeli policemen, armed with Thompsons meet a Jordanian legionnaire near the Mandelbaum Gate circa, 1960KNIL Soldier with an M1928A1 submachine gun, c. 1948.Thompson submachine guns were used by both sides during the 1948 Arab-Israeli war.<sup class="reference" id="cite_ref-31">[32] Following the war, Thompsons were issued to members of Israel’s elite Unit 101, upon the formation of that unit in 1953.<sup class="reference" id="cite_ref-Eilam_32-0">[33]

During the Greek Civil War, the Thompson submachine gun was used by both sides. The Hellenic Armed Forces, gendarmerie and police units were equipped with Thompson submachine guns supplied by the British and later in the war by the United States. The opposing Communist fighters of the Democratic Army of Greece were also using Thompson submachine guns, either captured from government forces or inherited from ELAS. ELAS was the strongest of the resistance forces during the period of Greek Resistance against the Germans and Italians, and were supplied with arms from both the British and the United States. After the demobilization of ELAS, an unspecified number of arms were not surrendered to the government but kept hidden, and were later used by the Democratic Army of Greece.<sup class="reference" id="cite_ref-Sazanidis_33-0">[34]

By the time of the Korean War, the Thompson had seen much use by the U.S. and South Korean military, even though Thompson had been replaced as standard issue by the M3/M3A1. With huge numbers of guns available in army ordnance arsenals, the Thompson remained classed as Limited Standard or Substitute Standard long after the standardization of the M3/M3A1. 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 Chinese Civil War. 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 captured and placed into service with American soldiers and Marines for the balance of the war.

During the Cuban Revolution, the Thompson submachine gun was used by some of Fidel Castro's 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 assault rifle. Not only did some U.S. soldiers have use of them in Vietnam, but they encountered them as well. The Vietcong liked the weapon, and used both captured models as well as manufacturing their own copies in small jungle workshops.

In the conflict in Northern Ireland, known as 'The Troubles' (1969–1998), the Thompson was again used by the Irish Republican paramilitiaries. According to historian Peter Hart, "The Thompson remained a key part of both the Official IRA and Provisional IRA arsenals until well into the 1970s when it was superseded by the Armalite and the AK-47."<sup class="reference" id="cite_ref-34">[35]

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.<sup class="Template-Fact" style="white-space: nowrap;">[citation needed]

The Thompson, or copies of the gun, are still seen from time to time in modern day conflicts, such as the Bosnian War.<sup class="Template-Fact" style="white-space: nowrap;">[citation needed]

Collector interest
Because of their quality and craftsmanship, as well as their gangster-era and WWII connections, Thompsons are sought as collector's items. There were fewer than forty pre-production prototypes. The Colt Patent Fire Arms Manufacturing Company in Hartford, Connecticut was contracted by the Auto-Ordnance Corporation to manufacture the initial mass production of 15,000 Thompson Submachine Guns in 1920. An original Colt Model 1921 A or AC, Model 1927 A or AC, Model 1928 Navy A or AC, properly registered in working condition with original components can easily fetch from US$25,000 to $45,000+ depending on condition and accessories. For WWII, approximately 1,700,000 Thompson Submachine Guns were produced by Auto-Ordnance and Savage Arms, with 1,387,134 being the simplified WWII M1 and M1A1 variants (without the Blish lock and oiling system<sup class="reference" id="cite_ref-35">[36] ). Post WWII, Numrich Arms acquired the Auto-Ordnance crated assets, but never resumed small-scale production of replica full automatic and semi-automatic only versions until 1974 at West Hurley. Semi-automatic only versions configured as civilian-legal rifles are currently produced by Auto-Ordnance Company (no relationship to the original 1916 AOC) a division of Kahr Arms, for the collector market at prices ($1100.00 to $1400.00) considerably lower than the prices for originals. A Model 1921A believed to have been owned by Bonnie and Clyde, but with zero historical documentation to substantiate this provenance, sold at auction on January 21, 2012 in Kansas City for $130,000.00.<sup class="reference" id="cite_ref-36">[37]

Operating characteristics
Early versions of the Thompson had a fairly high cyclic rate of fire, as high as 1,200rpm (rounds per minute), with most police Model 1921 at 850rpm and military Model 1928 at 720. Later M1 and M1A1 Thompsons averaged 600 rpm.<sup class="reference" id="cite_ref-Dunlap.2C_Roy_F._1948_p._299_37-0">[38] This rate of fire, combined with a rather heavy trigger pull and a stock with an excessive drop, increases the tendency for the barrel to climb off target in automatic fire.<sup class="reference" id="cite_ref-Dunlap.2C_Roy_F._1948_p._299_37-1">[38] <sup class="reference" id="cite_ref-George.2C_John_1981_p._395_38-0">[39] Compared to modern 9mm submachine guns, the .45 Thompson is quite heavy—weighing roughly the same as the contemporary M1 Garand battle rifle. This was one of the major complaints against the weapon made by servicemembers of militaries that issued the Thompson.<sup class="reference" id="cite_ref-rt66.com_16-1">[17]

Although the drum magazine provided significant firepower, in military service it was found to be overly heavy and bulky, especially when slung on patrol or on the march.<sup class="reference" id="cite_ref-George.2C_John_1981_p._395_38-1">[39] It was also rather fragile, and cartridges tended to rattle inside it, producing unwanted noise. For these reasons, the 20-round and later 30-round box magazines soon proved most popular with military users of the M1928A1, and drum compatibility was not included in the design of the wartime M1 and M1A1 models. The Thompson was one of the earliest submachine guns to incorporate a double-column, double-feed box magazine design, which undoubtedly contributed to the gun's reputation for reliability. In addition, the gun performed better than most after exposure to rain, dirt, and mud.<sup class="reference" id="cite_ref-rt66.com_16-2">[17]

The select fire (semi- or full automatic) Thompson fires from the "open bolt" position, in which the bolt is held fully to rearward by the sear when cocked. When the trigger is depressed, the bolt is released, traveling forward to chamber and simultaneously fire the first and subsequent rounds until either the trigger is released or the ammunition is exhausted. This eliminates the risk of "cook-off," which can sometimes occur in closed-bolt automatic weapons when the barrel becomes so hot that chambered rounds auto-ignite, causing the weapon to fire uncontrollably.

Disassembly
Thompson M1928A1, field strippedThe Thompson submachine gun field strips, depending on variant. World War 2 era M1 variants and RPB models field strip more easily than the M1921.

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 1919
The Model 1919 was limited to about 40 units, the first units built did not use the drums, as it was to difficult to fire. With many variations noted throughout. The weapons had very high cyclic rates around 1,500 rpm.<sup class="reference" id="cite_ref-39">[40] This was the weapon Brigadier General Thompson demonstrated at Camp Perry in 1920. Almost all Model of 1919s were made without buttstocks and front sights, and the final version closely resembled the later Model of 1921. The New York City Police Department was the largest purchaser of the Model of 1919. This model was designed as an automatic Colt .45 to "sweep" trenches with bullets. Some experimental calibers were .45 ACP (11.4x23mm), .22LR, .32 ACP, .38 ACP, and 9mmP.<sup class="reference" id="cite_ref-Fitz2487_15-2">[16]

Thompson .30 Carbine
<span style="padding: 0px; border: 1px solid rgb(170, 170, 170); color: rgb(0, 0, 0); font-size: xx-small;">‹The template Reference necessary is being considered for merging.› <span class="referencenecessary" style="border-bottom-color: rgb(204, 204, 204); border-bottom-width: 1px; border-bottom-style: dotted;">The layout and ergonomics of the Thompson submachine gun was also considered for the role of a Light Rifle before the adoption of the M1 Carbine. This platform was based on the M1921/27 variants and worked well but due to the war effort was found expensive for mass production and defied the concept of a Light Rifle. However it did form the basis of the Thompson Light Rifle, a development of this variant with a barrel shroud which housed a quick barrel change device similar to the MG42 but was refused in favor of the aforementioned M1 Carbine. <sup class="Template-Fact" style="white-space: nowrap;">[citation needed]

Model 1921
The "Anti-Bandit Gun": 1920s Advertisement of the Thompson M1921 for United States law enforcement forcesThompson Autorifle (top, upright) and SMG Model (bottom, inverted) of 1921The Model 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 an adjustable rear sight, a blued, finned barrel and vertical foregrip (or pistol grip) and the Blish lock. The M1921 was quite expensive to manufacture, with the original retail price around $200, because of its high-quality wood furniture and finely machined parts. The M1921 was famous throughout its career with police and criminals and in motion pictures. This model gained fame from its use by criminals during Prohibition, and was nicknamed "tommy gun" by the media.

Model 1923
The Model 1923 was a heavy submachine gun introduced to potentially expand the Auto-Ordnance product line and was demonstrated for the U.S. Army.<sup class="reference" id="cite_ref-40">[41] It fired the more powerful .45 Remington-Thompson cartridge which fired a heavier 250-grain (16,2 gram) bullet at higher muzzle velocities of about 1450 fps (440 m/s), with greater range than the .45 ACP. It introduced a horizontal forearm, improved inline stock for accuracy, 14-inch barrel, bipod and bayonet lug. The M1923 was intended to rival the M1918 Browning Automatic Rifle (BAR) with which the Army was already satisfied. The Army did not give the Model of 1923 much consideration, so it was not adopted.

Model 1921AC (1926)
While not a new model in the usual sense of incorporating major changes, in 1926 the Cutts Compensator (a recoil brake) was offered as an option for the M1921; Thompsons with the compensator were cataloged as No. 21AC at the original price of $200.00, with the plain M1921 designated No. 21A at a reduced price of $175.00.<sup class="reference" id="cite_ref-Frank_Iannamico_2000_22-1">[23] The Model 1921 was thereafter referred to as Model 1921A or Model 1921AC, though some collectors still refer to it as the Model 1921.

Model 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 Model 1928s were Model 1921s with weight added to the actuator, which slowed down the cyclic rate of fire, a U.S. Navy requirement. On these guns, the model number '1921' on the receiver was updated by stamping an '8' over the last '1'. The Navy Model 1928 has several names among collectors: the 'Colt Overstamp', 'The 1921 Overstamp', '28 Navy', or just '28N'.

The 1928 Thompson would be the last small arm adopted by the U.S. Army that used a year designation in the official nomenclature. With the start of World War II, major contracts from several countries saved the manufacturer from bankruptcy. A notable variant of the Model 1928 with an aluminium receiver and tenite grip, buttstock, and forend, was made by Savage.<sup class="reference" id="cite_ref-41">[42]

M1928A1
M1928A1 at Fort Knox, Kentucky, June 1942The 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. Though it could use both the 50-round drum and the 20- or 30-round box magazines, active service showed the drums were more prone to jamming, rattled when moving, and were too heavy and bulky on long patrols. 562,511 were made. Wartime production variants had a fixed rear sight without the triangular sight guard wings and a non-ribbed barrel, both like those found on the M1/M1A1.

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).

M1
Fire Controls M1 Thompson Front lever is selector switch set for full auto.Responding to a request further simplification, the M1 was standardized in April 1942 as the United States Submachine Gun, Cal. .45, M1. Rate of fire was reduced to approximately 600-700 rpm. First issued in 1943, the M1 uses a simple blowback operation, the charging handle was moved to the side, and the flip-up adjustable Lyman rear sight was replaced with a fixed L sight. Late M1 Thompsons had the triangular rear sight guard wings added to the L sight which was standardized on the M1A1 version. The slots adjoining the magazine well allowing use of the drum magazine were removed. The less expensive and more-easily manufactured "stick" magazines were used exclusively in the M1, with a new 30-round version joining the familiar 20-round type. The Cutts compensator, barrel cooling fins, and Blish lock were omitted while the buttstock was permanently affixed. Late production M1 stocks were fitted with reinforcing bolts and washers to prevent splitting of the stock where it attached to the receiver. The British had used improvised bolts or wood screws to reinforce M1928 stocks. The M1 reinforcing bolt and washer were carried over to the M1A1 and retrofitted to many of the M1928A1s in U.S. and British service.

M1A1
Both sides of the Thompson M1A1 shown with 30 round magazineThe M1A1, standardized in October 1942 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. The main difference between the M1 and M1A1 was the bolt. The M1 bolt had a floating firing pin and hammer, the bolt of the M1A1 had the firing pin machined to the face of the bolt, eliminating unnecessary parts. Other differences were that the reinforced stock was standard, the protective ears on the sight were standard, the magazine catch was modified (the M1 model used the same catch that was on the Model 1921 and 28 which was designed to accept drums), and the fire control switches were also redesigned to ease production. The 30-round magazine became more common. In 1939, Thompsons cost the government $209 apiece. By the spring of 1942, cost reduction design changes had brought this down to $70. In February 1944, the M1A1 reached a low price of $45 each, including accessories and spare parts, however the difference in price between the M1 and M1A1 was only $0.06. By the end of the Second World War, the M1A1 was replaced with the even lower-cost M3 (commonly called "Grease Gun").

Model 1927
The Model 1927 was the open bolt semi-automatic-only version of the M1921. It was made by modifying an existing Model 1921, including replacing certain parts. The "Thompson Submachine Gun" inscription was machined over to replace it with "Thompson Semi-Automatic Carbine", and the "Model 1921" inscription was also machined over to replace it with "Model 1927." Although the Model 1927 was semi-automatic only, it was easily converted to fully automatic by installing a full-auto Model 1921 fire control group (internal parts). Most Model 1927s owned by police have been converted back to full-auto.<sup class="reference" id="cite_ref-42">[43] The original Model 1927 is classified as a machine gun under the National Firearms Act of 1934 (a) by being "readily convertible" by swapping parts and (b) by a 1982 BATF ruling making all open bolt semi-automatic firearms manufactured after the date of this ruling classified as machineguns.

Model 1927A1
The Model 1927A1 is a semi-automatic only replica version of the Thompson, originally produced by Auto-Ordnance of West Hurley, New York for the civilian collector's market from 1974 to 1999. It has been produced since 1999 by Kahr Arms of Worcester, Massachusetts. It is officially known as the "Thompson Semi-Automatic Carbine, Model of 1927A1." The internal design is completely different to operate from the closed bolt and the carbine has barrel length of 16.5 inches (versus open bolt operation and barrel length of 10.5 inches (270 mm) for the full automatic versions). Under federal regulations, these changes make the Model 1927A1 legally a rifle and remove it from the federal registry requirements of the National Firearms Act. These modern versions should not be confused with the original semi-automatic Model of 1927 which was a slightly modified Model of 1921 produced by Colt for Auto-Ordnance.

The Model 1927A1 is the semi-automatic replica of the Thompson Models of 1921 and 1927. The "Thompson Commando" is a semi-automatic replica of the M1928A1. The Auto-Ordnance replica of the Thompson M1 and M1A1 is known as the TM1, and may be found marked "Thompson Semi-Automatic Carbine, Caliber .45M1".

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 pistol version, .45 ACP version of the Thompson originally produced by Auto-Ordnance in West Hurley. It featured an aluminum receiver to reduce weight. It has been produced since 2008 by Kahr Arms of Worcester, Massachusetts as the "M1927A1 TA5".

BSA Thompsons
In an attempt to expand interest and sales overseas, Auto-Ordnance entered into a partnership with and licensed the Birmingham Small Arms Company Limited (BSA) in England to produce a European model. These were produced in small quantities and have a different appearance than the classic style. The BSA 1926 was manufactured in 9mmP and 7.63mm Mauser and were tested by various governments, including France, in the mid 1920s. It was never adopted by any military force, and only a small number were produced.<sup class="reference" id="cite_ref-43">[44]

Special purpose variant
A special purpose machine pistol variant of the Thompson is manufactured by RPB Industries of Atlanta<sup class="reference" id="cite_ref-44">[45]

Silenced variant
A version with a threaded barrel for suppressors, side folding stock and modified sights.

Canada
Thompson submachine guns (including all variants or modified versions) are classified as Prohibited Weapons in Canada. Consequently, they cannot be legally imported or owned except under very limited circumstances. For example, to own one it must be "grandfathered" from before the bill was passed against it.<sup class="reference" id="cite_ref-45">[46] <sup class="reference" id="cite_ref-46">[47]

United States
Firing the 1921 ThompsonThe perceived popularity of submachine guns such as the Thompson with violent gangsters in the 1920s and 1930s was one of the main reasons given for passage of the National Firearms Act by the United States Congress in 1934. One of its provisions is that 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 restrictions on the possession, transfer, and transport of the weapons. For example, North Carolina restricts fully automatic weapons except for soldiers, law enforcement, and merchants with a permit who need them to defend their business.<sup class="reference" id="cite_ref-47">[48]

There are several U.S. made automatic and semi-automatic variants, copies, or replicas. The semi-automatic versions are less regulated by federal law.

Users

 * Australia Used by Australian forces during WWII until it was replaced by the Australian-made Owen submachine gun.
 * Canada<sup class="reference" id="cite_ref-48">[49]
 * People's Republic of China: Limited, sometimes unlicensed copies.<sup class="reference" id="cite_ref-History_49-0">[50] <sup class="reference" id="cite_ref-50">[51]
 * Republic of China<sup class="reference" id="cite_ref-mcnab2002_51-0">[52]
 * Croatia<sup class="reference" id="cite_ref-bishop1998_2-3">[3]
 * France<sup class="reference" id="cite_ref-History_49-1">[50]
 * Greece Used by Greek armed forces, resistance fighters,  Gendarmerie  and police units during World War II and immediately postwar.<sup class="reference" id="cite_ref-Sazanidis_33-1">[34] <sup class="reference" id="cite_ref-mcnab2002_51-1">[52]
 * Haiti<sup class="reference" id="cite_ref-gander1995_52-0">[53]
 * India<sup class="reference" id="cite_ref-mcnab2002_51-2">[52] Used by Chindits in Burma campaign
 * Indonesia Used by Indonesian Army Special Forces in 1950-1970s
 * Ireland: 123 used by the Irish Defence Forces during the Emergency.
 * Israel:<sup class="reference" id="cite_ref-Eilam_32-1">[33]
 * Italy: Captured examples pressed into use by the Italian Army prior to September 8, 1943.<sup class="reference" id="cite_ref-53">[54] Also supplied to partisans and to the Italian Co-Belligerent Army.<sup class="reference" id="cite_ref-54">[55] After the war, it was mostly issued to Italian Air Force troopers<sup class="reference" id="cite_ref-55">[56] and the Carabinieri.<sup class="reference" id="cite_ref-56">[57]
 * Luxembourg: M1A1 in service 1952-1967, replaced by Uzi.<sup class="reference" id="cite_ref-57">[58]
 * Nazi Germany: Captured from United States Army, limited use in Second World War<sup class="Template-Fact" style="white-space: nowrap;">[citation needed]
 * The Netherlands: In early World War II, at least 3,680 Thompsons acquired through Lend-Lease.<sup class="reference" id="cite_ref-Frank_Iannamico_1928_11-1">[12]
 * New Zealand<sup class="reference" id="cite_ref-bishop1998_2-4">[3]
 * North Vietnam: Unlicensed copies.<sup class="reference" id="cite_ref-History_49-2">[50] Used by North Vietnamese soldiers in the First Indochina War
 * Portugal: Small number bought for police use, designated m/1928<sup class="reference" id="cite_ref-58">[59]
 * Republic of Korea: Captured by People's Liberation Army and limited number received from U.S. government; limited use in Korean War and Vietnam War
 * South Vietnam<sup class="reference" id="cite_ref-bishop1998_2-5">[3]
 * Soviet Union<sup class="reference" id="cite_ref-TG_59-0">[60]
 * Sweden<sup class="reference" id="cite_ref-60">[61]
 * Turkey:Limited received by U.S.government used at Korean War
 * United Kingdom<sup class="reference" id="cite_ref-miller2001_61-0">[62]
 * United States: Employed by the United States Marine Corps<sup class="reference" id="cite_ref-62">[63] and by United States Army 1938.<sup class="reference" id="cite_ref-miller2001_61-1">[62]
 * West Germany: Limited number received from U.S. and Used at Nazi Germany
 * Yugoslavia<sup class="reference" id="cite_ref-63">[64]
 * Malaysia
 * Philippines

Non-state groups

 * American organized crime syndicates, such as the Chicago Outfit and American Mafia.
 * The Provisional IRA used the 1921 variant, mainly during the early 1960s to 1970s.<sup class="reference" id="cite_ref-64">[65]