[Encyclios]

Terminal ballistics

Terminal ballistics studies the effects of the projectile on the target and the causes behind them, such as mechanical characteristics and residual velocity at impact. In the case of non-explosive projectiles, the main factors are the residual energy expressed in kilogrammeters, the penetration coefficient and the consistency of the bullet tip.

The study is often aimed at maximizing the stopping power of ammunition, with regard not only to the caliber, but above all to the structure of the bullet, and this is even more so when used for personal defense purposes. In fact, for personal defense it is not important that the bullet be lethal, but rather that it stop the aggressor. Terminal ballistics therefore studies the deformations that the bullet undergoes at the moment of impact, any fragmentations that must be avoided, and the shape that the bullet assumes depending on the type of ammunition (jacketed, armored, half jacketed, naked, etc.).

A bullet that penetrates the body by passing through it transmits only part of the kinetic energy it possesses to the target, and therefore has a low stopping power. In this case, the projectile can be lethal but often does not transmit to the target the shock necessary to stop it instantly and avoid a dangerous hostile response. The stopping power is in fact related to the amount of kinetic energy present at impact and the percentage of this that is transmitted to the target.

The study of the terminal ballistics of a projectile is therefore important: a projectile that deforms on impact, assuming the classic mushroom shape, will be easily stopped by the body of the target that will absorb all the kinetic energy; the shock effect and therefore the stopping power will be maximized. This is the case of hollow point bullets, which are forbidden by Italian law for personal defense purposes, while armored bullets are allowed, similar to those used for military purposes, which have the characteristic of being less lethal.

Depending on their intended purpose, bullets are divided into armor-piercing, expanding, and frangible; on living targets, the most devastating results are obtained with expansive, soft-tipped, possibly perforated bullets. Small caliber bullets animated by very high velocities, greater than 1000 m/s, give rise to explosive phenomena due to the pressure wave on impact against living tissue and are therefore much more destructive than bullets of higher caliber, but slower.

All fast projectiles produce an exit hole much larger than the entry hole, behaving similarly to expansive projectiles. Explosive projectiles exhibit impact behavior consequent to the type and quantity of the charge. In this regard, the most important phenomenon is the Munroe effect, universally exploited in hollow-charge armor-piercing projectiles.

In 1888 the American chemist C. E. Munroe (1849-1938) discovered that when the charge is placed in such a way as to present a conical cavity at the tip of the projectile, on impact the energy of the explosion is concentrated in a small central area and generates a dart capable of perforating ten times the thickness of steel.