A firearm is a portable gun, being a barreled weapon that launches one or more projectiles often driven by the action of an explosive force.〔(US Federal Govt ) does not consider an air gun to be a firearm and does not regulate them as firearms〕 The first primitive firearms were invented in 13th century China when the one-person-portable fire lance was combined with projectiles. The technology gradually spread through the rest of East Asia, South Asia, Middle East and then into Europe. In older firearms, the propellant was typically black powder, but modern firearms use smokeless powder or other propellants. Most modern firearms (with the notable exception of smoothbore shotguns) have rifled barrels to impart spin to the projectile for improved flight stability.
Modern firearms are usually described by their caliber (i.e. their bore diameter, this is given in millimeters or inches e.g. 7.5mm, .357) or in the case of shotguns their gauge (e.g. 12 ga.); the type of action employed (muzzle, breech, lever, bolt, pump, revolver, semi-automatic, automatic e.t.c.) together with the usual means of deportment (hand-held or mechanical mounting). They may be further distinguished by reference to the type of barrel used (rifled) and the barrel length (19 inch), the design's primary intended use (e.g. hunting rifle), or the commonly accepted name for a particular variation (e.g. Gatling gun). The word ''firearms'' usually is used in a sense restricted to small arms (weapons that can be carried by a single person), whereas the word ''artillery'' covers larger gunpowder-fired weapons.
Firearms are aimed visually at their targets by hand using either iron sights or optical sights. The accurate range of pistols is generally limited to , while most rifles are accurate to using iron sights, or longer ranges using optical sights (firearm rounds may be dangerous or lethal well beyond their accurate range; minimum distance for safety is much greater than specified range). Some purpose-built sniper rifles are accurate to ranges of more than .
==Types of firearms==
抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』
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