Handgun ammo

A cartridge or round is a single unit of ammunition typically comprising four components:

• Bullet: Sometimes, the entire cartridge is referred to erroneously as the bullet, but the bullet is simply the projectile — the only component, except for solid and gaseous combustion products — to leave the barrel. In the United States, manufacturers measure bullet weights in grains (1/7,000th of a pound), while in many other countries, measurements are in grams.
• Powder: The propellant charge that drives the bullet through the barrel. It burns slowly rather than detonating when ignited, causing a buildup of high-pressure gas in the cartridge case. This pressure expands the cartridge case inside the chamber, obturating (sealing) the breach.
• Primer: This is the primary explosive charge contained inside a centrally located metallic cup (centerfire) or in a section along the rim (rimfire) that contains the primary explosive charge (primer). When struck by the hammer or striker, the primer detonates, sending burning particles into the propellant charge. This action ignites it, firing the round.
• Case: Also called the shell, the cartridge case or casing holds the other three components together in a self-contained, environmentally sealed, and durable package. In automatic and semi-automatic firearms, the cartridge case absorbs heat from the burning propellant, removing it from the weapon. The case also has an extractor flange, or rim, to enable extraction from the firing chamber.