Editing Thompson submachine gun (section)

===Service variants===
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====Thompson Machine Carbine (TMC)====
In 1940, Commonwealth troops in Egypt and North Africa were issued commercial model Lend-Lease Colt- and Savage-manufactured M1928s. Section leaders carried them instead of pistols or rifles. Many of the Colt models had French-language manuals packed with them as they had been abruptly diverted to England after the fall of France. They soon discovered that the weapon was prone to jamming due to sand. To fix this, the armorers removed the Blish Lock and replaced it with a hex bolt to keep the cocking handle and bolt together. The 20-round Type XX magazines had their peep-holes welded shut to keep sand out and the 50-round Type L drums were discontinued. Ammunition was scarce as it was either in small lots of Lend-Lease commercial ammo or obtained from adjacent American troops. It was later replaced by the [[9mm Parabellum|9mm]] [[Sten gun]] and [[Lanchester SMG]].

Models used in the Pacific by Australian troops had their sling swivels remounted on the left side to allow it to be fired more easily while prone. A metal sling mount was fitted to the left side of the wooden buttstock. Ammunition was manufactured in Australia or obtained from adjacent American troops. It was later replaced by the [[Owen Gun|Owen Machine Carbine]].

====M1====
[[File:Thompson submachine gun Firecontrols.jpg|thumb|Fire controls on an M1 Thompson. Front lever is the selector switch, set for semi-automatic fire.]]

Responding to a request for 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&nbsp;rpm.

First issued in 1943, the M1 uses a simple [[Blowback (arms)|blowback]] operation, with the charging handle moved to the side. The flip-up adjustable Lyman rear sight was replaced with a fixed L sight. Late M1s had triangular guard wings added to the rear L sight, which were standardized on the M1A1. The slots adjoining the magazine well allowing the use of a drum magazine were removed. A new magazine catch with the provision for retaining drum magazines removed, was produced, but most M1s and later M1A1s retained the original. 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 [[Stock (firearms)|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 American and British service. Late M1s also had simplified fire control switches, also carried over to the M1A1. Certain M1s had issues with high rate of fire climbing up to ~800 RPM. The exact cause remains unknown, but was resolved with the transition to the M1A1.<ref>[https://smallarmsreview.com/display.article.cfm?idarticles=2163 M1 Vs M1A1 Thompson Submachine Gun Cyclic rate]</ref>

====M1A1==== <!-- [[M1A1]] links here -->
[[File:ThompsonM1A1VWM.jpg|thumb|right|The M1A1 Thompson submachine gun on display at the Virginia War Museum.]]

The 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, and the bolt of the M1A1 had the firing pin machined to the face of the bolt, eliminating unnecessary parts. The reinforced stock and protective sight wings were standard. 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, although the difference in price between the M1 and M1A1 was only $0.06. By the end of the war, the M1A1 was replaced with the even lower-cost M3 (commonly called the "Grease Gun").