A machine pistol is a handgun-style, magazine-fed and self-loading firearm, capable of fully automatic or burst fire, and normally chambered for pistol cartridges. The term is a literal translation of Maschinenpistole, the German term for a hand-held automatic weapon. While the dividing line between machine pistols and compact submachine guns is hard to draw, the term "submachine gun" usually refers to larger automatic firearms scaled down from that of a full-sized machine gun, while the term "machine pistol" usually refers to a weapon built up from a semi-automatic pistol design.
In a law enforcement context, machine pistols are used by tactical police units such as SWAT teams or hostage rescue teams which are operating inside buildings and other cramped spaces, who need a small, concealable weapon with a high rate of fire. Bodyguards from police or government agencies sometimes carry concealed machine pistols when they are protecting high-risk VIPs. Criminal gang members such as narcotics traffickers also use machine pistols, typically cheaper guns such as the MAC-10 or the Tec-9 which have been illegally converted to fire in a fully-automatic fashion.
In a military setting, some countries issue machine pistols as personal defense sidearms to paratroopers, artillery crews, helicopter crews or tank crews. They have also been used in close quarters combat (CQC) settings where a small weapon is needed (e.g. by special forces attacking buildings or tunnels). In the 2000s, the machine pistol is being supplanted by the personal defense weapon: a compact, fully-automatic submachine gun-like firearm which fires armour-piercing rounds instead of pistol ammunition.
