Bullet

A bullet is a kinetic projectile and the component of firearm ammunition that is expelled from the gun barrel during shooting. The term is from Middle French and originated as the diminutive of the word boulle (boullet), which means "small ball". Bullets are made of a variety of materials such as copper, lead, steel, polymer, rubber and even wax. They are available either singly as in muzzleloading and cap and ball firearms or as a component of paper cartridges, but much more commonly in the form of metallic cartridges. Bullets are made in a large number of shapes and constructions depending on the intended applications, including specialized functions such as hunting, target shooting, training and combat. Though the word "bullet" is often used incorrectly in colloquial language to refer to a cartridge round, a bullet is not a cartridge but rather a component of one. A round of ammunition cartridge is a combination package of the bullet (which is the projectile), the case (which holds everything together), the propellant (which provide majority of the energy to launch the projectile) and the primer (which ignites the propellant). This use of the term "bullet" when intending to describe a cartridge often leads to confusion when the components of a cartridge are specifically referred to. Bullet sizes are expressed by their weights and diameters (referred to as "calibers") in both imperial and metric measurement systems. For example: 55 grain .223 caliber bullets are of the same weight and caliber as 3.56 gram 5.56mm caliber bullet