Headshots Anatomy

A headshot, at first glance, seems like a surefire route to fatality. When a bullet from a pistol or rifle enters someone's skull, it initiates a complex chain of events that extends beyond the macabre reality. However, not all headshots are equal in lethality. To begin our exploration, we'll limit our discussion to pistols and rifles, as the consequences of a shotgun blast to the head are tragically self-evident.

Let's start our journey at the firearm itself. When a bullet is discharged from a pistol or rifle, it traverses through a rifled barrel. These barrels feature grooves that induce a spinning motion in the bullet. This rotation is pivotal in understanding the damage caused by a headshot.

As the spinning bullet breaches the skull, it exerts a rotational force that flings cranial tissue outward. This outward movement causes the tissue to expand, ballooning to roughly 12.5 times the bullet's diameter. However, this expansion is extremely short-lived, occurring within a span of 5 to 10 milliseconds, after which the tissue reverts to its normal size. To illustrate, a 22-caliber bullet generates a wound approximately 2.7 inches in diameter. In contrast, a 38-caliber bullet yields a wound measuring 4.4 inches, while a 45-caliber bullet results in a wound that spans five inches. Despite its brevity, this rapid tissue expansion inflicts considerable damage on the skull.

The initial wound also initiates a vacuum effect, drawing in air and causing the cranial cavity to expand. This expansion leads to the formation of secondary fracture lines radiating from the wound, predominantly in vulnerable areas like the temples and orbital plates behind the eyes. It's noteworthy that higher-powered firearms tend to produce more secondary fracturing, especially in the denser regions at the front and back of the skull.

Now, let's delve into what distinguishes a bullet's lethality. Weight, length, and velocity are crucial factors to consider, but it is velocity that stands as the primary determinant of a bullet's damage potential. This principle can be elucidated through an examination of kinetic energy, as defined in the equation:

Kinetic Energy = (Bullet Weight × Bullet Velocity^2) / (2 × Gravitational Acceleration Constant)

To simplify this concept, think of it as more velocity equating to more damage. When a bullet possesses higher kinetic energy, it inflicts more substantial harm. Mathematically, the correlation between velocity and damage is evident. If we designate all factors as a value of 10, the kinetic energy equals 50. Doubling the bullet's weight results in the kinetic energy doubling as well, reaching 100. However, doubling the bullet's velocity does not lead to double the energy; instead, it quadruples it. Hence, greater kinetic energy equates to a stronger pressure wave through the skull, increased penetration, and more pronounced external gases entering the head.

This explanation elucidates why rifles are more lethal than pistols, not due to bullet weight, but owing to the bullet's velocity. Now that we've discussed the exterior damage, let's explore the bullet's journey within the skull.

When a bullet punctures the skull, it generates an entrance wound approximately the same size as the bullet itself. If the bullet exits the skull, it creates an exit wound far larger than the bullet's dimensions. This phenomenon occurs across various media, be it plastic, metal, wood, or bone. The bullet's passage induces a shockwave, widening the path ahead of it. Moreover, the bullet may fragment or mushroom upon impact, further increasing the damage it inflicts.

Inside the skull, the bullet alters the bone structure, causing the beveling of the bone's edge. Once inside the brain, several outcomes are possible for the bullet. It may come to a gradual halt, ultimately resting inside the brain, often near the opposite end of the skull. Alternatively, it can pass through the brain, or in the case of high-velocity rounds, it may ricochet within the head. Interestingly, most skull ricochets involve the bullet following the skull's rounded grooves instead of an angular bounce-off.

The brain, a soft, inelastic organ, doesn't benefit from its properties when it comes to gunshot wounds. While elastic organs like intestines or the stomach may withstand gunfire relatively well due to tissue stretching and energy dissipation, solid and inelastic organs, such as the brain, are severely affected. The pressure wave generated by the bullet results in massive damage to inelastic organs, as their tissue does not stretch.

The brain's vulnerability is further exacerbated when the bullet's distance from the barrel to the head is taken into account. In instances where the shot is from a considerable distance, the bullet might bounce off the head, inflicting severe damage without penetrating the skull. These shots are typically over 100 yards away and are discharged from low-powered firearms like pistols or .22 caliber weapons.

It's crucial to remember that while headshots are undoubtedly devastating, they are not always fatal. On average, they result in death 90% of the time, contingent on various factors and circumstances.