Wednesday, May 15, 2013

Thompson submachine gun









Thompson is a subbmachinegun use by the USE.It was invented by John T. Thompson.



History and service    

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.Thompson found a financial backer, Thomas F. Ryan, and started the Auto-Ordnance Company in 1916 for the purpose of developing his auto rifle. It was primarily developed in Newport, Kentucky. 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.

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". 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. This concept had already been developed by German troops using their own Bergmann MP18, the world's first submachine gun, in concert with sturmtruppen tactics.

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 (to protect the mail from a spate of robberies) 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.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.
Archetypal gangster image of a Thompson in a violin case
The 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."
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.
In 1928 Federal Laboratories took over distribution of the weapon from Thompson's Auto Ordnance Corporation. The cost at this time was US$225 per weapon, with $5 per 50-round drum and $3 for 20-round magazine.
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.

Features 

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.[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.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.
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.[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.
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.



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