Patruunat

Patruunat, the Finnish term for cartridges, are self-contained firearm ammunition designed to deliver a projectile to a target. A cartridge integrates four elements into a single unit: a case, a propellant charge, a primer, and a projectile. The case contains and encloses the propellant and primer and provides the physical support for the bullet. When ignited, the propellant rapidly generates high-pressure gas that drives the bullet down the bore.

Cartridges are built in two main mechanical styles: rimfire and centerfire. Rimfire cartridges have the primer distributed around the rim of the case base, while centerfire cartridges use a separate primer seated in a dedicated primer pocket. Some shotgun ammunition uses a different form factor altogether, such as shells with multiple projectiles or slugs.

Projectiles vary: bullet shapes include full metal jacket, soft point, and hollow point, each with different performance in terms of penetration, expansion, and terminal effect. Calibers range widely, from small pistol cartridges to large rifle rounds. The choice of case material (brass, steel, aluminum) affects durability, reloadability, and cost. Modern patruunat are standardized for safety and interchangeability in many jurisdictions by organizations such as SAAMI and CIP.

History and use: The self-contained cartridge emerged in the 19th century, enabling mass production and standardized ammunition. Today patruunat are used in military, law enforcement, hunting, and sport shooting, with regulatory frameworks varying by country.