Submachine gun

A submachine gun (SMG) is an air-cooled, magazine-fed, automatic carbine designed to fire pistol cartridges. The term "submachine gun" was coined by John T. Thompson, the inventor of the Thompson submachine gun.

The submachine gun was developed during World War I (1914–1918). At its zenith during World War II (1939–1945), millions of SMGs were made. After the war, new SMG designs appeared frequently. However, by the 1980s, SMG usage decreased. Today, submachine guns have been largely replaced by assault rifles, which have a greater effective range and are capable of penetrating the helmets and body armor used by modern infantrymen. However, submachine guns are still used by military special forces and police SWAT teams for close quarters battle (CQB) because they're "a pistol caliber weapon that's easy to control, and less likely to over-penetrate the target."

There are some inconsistencies in the classification of submachine guns. British Commonwealth sources often refer to SMGs as "machine carbines". Other sources refer to SMGs as "machine pistols" because they fire pistol-caliber ammunition, for example, the MP-40 and MP5, where "MP" stands for Maschinenpistole ("machine pistol" in German). However, the term "machine pistol" is also used to describe a handgun-style firearm capable of fully automatic or burst fire, such as the Stechkin, Beretta 93R and the H&K VP70. Personal defence weapons (PDW) such as the FN P90 and H&K MP7 are also commonly referred to as submachine guns. In addition, some compact assault rifles, such as the Colt XM177, HK53 and AKS-74U, are also referred to as SMGs, because they are used in the submachine gun role.

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