Pistols and rifles

Modern firearms can be described by their caliber (the diameter of the iron). For pistols and rifles, it is given in millimeters or inches (eg 7.62 mm or 0.308 inches). For shotguns, by their gauge (eg 12 ga – 20 gauge).

Firearms are also described by type of action (e.g. bolt, pump, revolver, semi-automatic, fully automatic, etc.)

Additional classification may refer to the type of barrel used (ie, rifle) and barrel length (eg, 11-24 inches), the firing mechanism, the primary use of the design (eg, shotgun), or the commonly accepted name of a particular variation (eg, Gatling gun).