Sub-machine gun

A submachine gun (SMG) is a 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 are "a pistol caliber weapon that's easy to control, and less likely to over-penetrate the target."

In the early 20th century, experimental machine pistols were made by converting pistols such as the Luger P-08 and Mauser C96 from semiautomatic to fully automatic operation and adding detachable stocks. Carbine-type automatic weapons firing pistol rounds were developed during the latter stages of World War I by Italy, Germany and the United States. Their improved firepower and portability offered an advantage in trench warfare.

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