Bullet: projectile, cartridge components, types, history and uses

Basic components and how they work

A cartridge or round of ammunition holds the elements required to fire a bullet. The primer, when struck by the firing mechanism, creates a small ignition that lights the propellant (commonly called gunpowder in traditional terms). Rapid combustion of the propellant generates high-pressure gas that drives the bullet forward through the barrel and toward the target. The case keeps these parts together and is designed to fit a specific chamber and barrel.

Common types and characteristics

• Full metal jacket (FMJ): a soft core, often lead, fully enclosed by a harder jacket to reduce deformation.
• Hollow-point: a cavity in the tip that encourages expansion on impact, used in many self-defense and hunting contexts.
• Soft point: exposes the core at the tip to provide controlled expansion.
• Match and boat-tail designs: optimized for accuracy and stability at range, often used in target and hunting rifles.

Bullets have a size, usually referred to by caliber (diameter) and sometimes by the cartridge designation. Different firearms — from pistols to high-powered rifles — require specific calibers and case types to function safely and accurately.

History and development

Projectiles evolved from simple lead spheres and early conical shapes to more sophisticated bullets as rifling, metallurgy, and propellant chemistry advanced. The introduction of rifled barrels increased accuracy by imparting spin, and the development of jacketed bullets and new propellants improved velocity, stability, and terminal performance. Ammunition manufacturing became standardized so that cartridges and firearms from different makers could be reliably matched.

Uses, legal and safety considerations

Bullets and cartridges are used by soldiers, police, sport shooters and hunters (hunting). They are also employed for personal protection and in many civil and recreational contexts. Because bullets are weapons when assembled and fired, their manufacture, sale, possession and transport are regulated in most jurisdictions. Safe handling, secure storage, and appropriate training are important to reduce accidental injury.

Notable distinctions and environmental issues

It is important to distinguish between the bullet (the projectile) and the cartridge or round. Ammunition comes in two broad primer categories: rimfire and centerfire; most modern military and civilian cartridges are centerfire because of greater reliability and ease of reloading. Lead in bullets and shot can contaminate soil and water at shooting ranges, prompting the use of non-lead alternatives and range management practices. Shotguns fire shells that may contain many small pellets or a single slug, which are functionally different from single-projectile bullets.

For an overview of firearms and safe practices see general resources on guns and ammunition, and consult manufacturers' guidance on specific cartridges such as the cartridge type used in a given firearm. Technical primers explain ignition and chambering in more detail; for instance, a primer ignites the propellant which produces the gases that expel the bullet. For more technical reading on propellants and cartridge design follow materials indexed at relevant specialist references: ammunition guidance, propellant chemistry, and resources about projectiles and bullet construction.

When studying or handling ammunition, also review legal and environmental guidance from authorities where you live and seek practical training from qualified instructors to ensure responsible use.

Guns • Lead • Copper • Cartridge • Gunpowder • Weapons • Soldiers • Police • Hunting • Caliber • Ammunition • Projectile • Propellant