cartridge

A modern round consists of the following: Bullet, as the projectile Cartridge case, which holds all parts together Propellant, for example, gunpowder or cordite Rim, which allows the firearm's extractor to grip the casing to remove it from the chamber Primer, which ignites the propellant

A cartridge, also known as a round, is a type of pre-assembled firearm ammunition packaging a projectile (bullet, shot, or slug), a propellant substance (smokeless powder, black powder substitute, or black powder) and an ignition device (primer or percussion cap) within a metallic, paper, or plastic case that is precisely made to fit within the barrel chamber of a breechloading gun, for convenient transportation and handling during shooting. Although in popular usage the term "bullet" is often used to refer to a complete cartridge, the correct usage only refers to the projectile.