The invention relates to ammunition suitable for firing from a self-loading sidearm comprising a cartridge adapted to fire a projectile, the cartridge case having at one end a portion of reduced diameter, the projectile being held in the said portion of reduced diameter, wherein the ratio of the external diameter of the cartridge case at its widest point to the external diameter of the projectile at its widest point is such that when the projectile is fired into a target high velocity wounding is caused. The invention also relates to a gun barrel for a self-loading sidearm through which the ammunition can be shot, and a self-loading sidearm comprising such a barrel.