The science of projectiles and firearms is defined as ‘ballistics’ and it can be divided into three distinct categories: internal, external and terminal. Internal ballistics is concerned with what happens within a time span of about two milliseconds, from the impact of the firing pin or striker, to the exit of the bullet or shot-charge from the muzzle end of the barrel. External ballistics is concerned with the flight of the bullet or shot-charge after leaving the barrel. Terminal ballistics deals with that which takes place when the bullet or shot-charge strikes the target.
When using firearms to kill animals at close quarters, it is the terminal ballistics that are most relevant. During the short period of interaction between a projectile and its target, the projectile will undergo some degree of distortion or disintegration and the target will be pierced and subsequently damaged. The amount of distortion and ensuing damage is dependent upon the mass of the projectile, its design and construction, its striking velocity, the angle of incidence and the nature of the target.
It is very important to appreciate that whatever weapon is chosen to carry out the killing of the animal, that weapon is only the means of delivery. It is the projectile discharged from the firearm which kills the animal, or not, as the case may be. Bullets or shot-charges used for humane destruction must have the properties which enable them to transfer sufficient energy to concuss the animal instantaneously, penetrate the skull to a level beyond the brain stem, and distort sufficiently to destroy much of the brain, brain stem and upper spinal cord.
For these reasons, the ideal ammunition is one which expands upon impact and dissipates its energy within the brain cavity. The ideal performance of an expanding bullet is achieved when the nose material peels back upon itself to form the classic ‘mushroom shape’ at the correct depth of penetration in the animal’s head. This expansion must be achieved without the bullet breaking up or suffering an unacceptable degree of weight loss. The expanded bullet should also utilise its potential for tissue destruction at the optimum point of penetration, to cause maximum destruction in the internal area containing the mid-brain and brain stem. At the same time, however, the bullet should not over-penetrate and cause consequent danger to objects or persons beyond the intended target.
Ammunition must:
Concuss
Penetrate
Distort
Destroy
