The damaging power of the shot is not only determined by its mass and velocity, but also it is a consequence of the relationship between the characteristics of the projectile and those of the game. The number of wounds inflicted determinants for the killing of the game, in turn, depends on other additional variables such as the distance of the shot, the size of the animal and its strenght, all those characteristics of the weapon that shoots and that interact on the dispersion of the shot pattern, and, then, on the string of the same (choke of the barrel, the number of shot of the charge, presence of the container in the cartridge, etc …).
In physics the energy is defined as the ability possessed by a body to produce work, and in the case of the shot the work is to be understood as to download the energy on the game, via the impact on its body. Indeed, the powder burning in the barrel of the gun, producing a large quantity of gaseous mass, produces a work which in part is dispersed as heat, and in part is exploited to launch a projectile.
In physics the energy that a shot has in his direction is defined “kinetic”, and it is amechanical energy of a body in motion (the shot), that is, the work done by the shot crossing the body of the game; in other terms it’s equivalent to the difference between impact energy and residual energy after the crossing.
Therefore, to calculate the kinetic energy of a bullet, at the various shooting distances, it is sufficient to know its mass (weight) and the residual velocity. In any case, the kinetic energy of the shot depends on several factors, such as speed and size of the shot, the physical size of the game and its natural defenses, such as thickness and strength of the skin, plumage, muscles, adipose or connective tissues …
The kinetic energy required for the killing increases, then, in relation to the mass, and the defenses of the animal. This amount of energy can be brought on the game both by a large shot at a low speed, either by a small and fast shot, but with different damaging capacity.
The first will have a lesion type trauma, the second will cause a deep wound. The kinetic energy that it is downloaded on the game is the sum of the energies of the individual shot that come on the target, the same amount of energy can therefore be carried by a few big shot, as many small shot.
To have success in shooting, we have to inflict more wounds, choosing the numbering of lead that ensures a sufficient residual energy and an appropriate density of shot pattern.
The general Journée, historical and scientist of ballistic, stated that the clean killing of game could be achieved with only 5 shot of adequate size. These have to be able both to harm the vital organs that to break the long bones. And to do that, they had to be equipped with adequate speed able to ensure the correct amount of energy.