hylsyjä

Hylsyjä refers to ammunition casings, also known as cartridge cases or shells. These are the cylindrical containers that hold the primer, propellant, and projectile of a firearm cartridge. The primary function of a hylsy is to seal the breech of the firearm during firing, preventing gas from escaping, and to extract the spent cartridge after the shot is fired.

Hylsyjä are typically made from brass, although steel, aluminum, and even plastic are used in some applications. The design and dimensions of a hylsy are crucial for its compatibility with a specific firearm and caliber. They come in various shapes, including rimmed, rimless, semi-rimmed, and belted, each offering different advantages for feeding and extraction mechanisms in firearms.

After firing, the hylsy expands slightly due to the pressure of the explosion, creating a gas-tight seal. Upon unlocking of the firearm's action, the hylsy is then ejected, either manually or automatically, making way for the next round. Spent hylsyjä are often collected for reloading, a practice where the casing is cleaned, resized, and refilled with propellant, primer, and projectile to create new ammunition. This can be a cost-effective and environmentally conscious way to continue using ammunition. The study and identification of different types of hylsyjä are important in forensic ballistics for identifying firearms and the ammunition used.