The term bullet is from Early French, originating as the diminutive of the word boulle ( boullet), which means 'small ball'. Bullets do not normally contain explosives but strike or damage the intended target by transferring kinetic energy upon impact and penetration. Bullet size is expressed by weight and diameter (referred to as ' caliber') in both imperial and metric measurement systems. Bullets are often tapered, making them more aerodynamic. They are made of a variety of materials, such as copper, lead, steel, polymer, rubber and even wax and are made in various shapes and constructions (depending on the intended applications), including specialized functions such as hunting, target shooting, training, and combat. The three bullets on the right show cannelure evolution Schlieren image sequence of a bullet traveling in free-flight, demonstrating the air pressure dynamics surrounding the bulletĪ bullet is a kinetic projectile, a component of firearm ammunition that is shot from a gun barrel. 7.5×55mm Swiss full metal jacket, armor piercing, and tracer, spitzer projectiles. For other uses, see Bullet (disambiguation). This article is about firearms projectiles.
