Wound Ballistics

Injuries and Wounds

As per Section 44 of the Indian Penal Code, the word ‘injury’ denotes any harm caused to any person in body, mind, reputation, or property. A wound is an injury to the body leading to a breach in the continuity of tissues, usually skin or mucous membrane. Different types of wounds are caused by the use of different means such as knives, firearms, blunt objects, acids & alkalis, dangerous radiations using Ultra Violet light, X-rays, or radioactive substances.

Firearm injuries are caused by using weapons like revolvers, pistols, rifles, shotguns, etc. The nature of firearm injuries caused by firearms depends on a large number of factors including the type of weapon, velocity of the projectiles, firing range among others.

Normally, where a knife or similar weapon can cause a single wound at a time (or let’s say a blow), firearms are capable to produce more than that.

Introduction to Wounding Mechanism

When a bullet hits the human body, the skin, flesh, and bone beneath it depress and compresses. The constant pressure extends them beyond their elastic limitations, resulting in a hole. After the hole is made and the bullet has entered, the stretched skin returns to its original state. As a result, the diameter of the hole in the skin appears to be smaller on non-stretched skin than the size of the projectile that generated the wound when it was stretched.

The minimum velocity necessary to penetrate the human skin is 40 to 50 meters per second. The penetrating velocity of a bone is found to be 60 meters per second. The projectile continues to move forward until it leaves the body through an exit hole, or until its energy is consumed in overcoming the resistance. The projectile may be found wedged at the end of the path of the wound in several cases.

Types of Firearm Injuries

There are two types of firearm injuries:

Forensic Significance

The projectiles fired by firearms have certain shapes, velocities, and kinetic energies which vary from most of the other agents causing injuries. The shapes of the wound, the destructive effect on the tissues, the presence of foreign bodies (of specific shapes and composition), and the projectile trajectory help to ascertain whether the given injury is a firearm injury or not.

The evaluation of the injuries elucidate if the given injury is-

  • A firearm injury or not
  • An entrance wound or an exit wound
  • Post- mortem or antemortem injury
  • Fired from the alleged firearm or not
  • Lethal or not

The evaluation of injuries can also point out the alleged number of shots fired or the number of firearms used.

Entry Wound

They are either penetrating or perforating. Penetrating wounds occur when a bullet enters an object and does not exist. The bullet goes completely through the object in perforating wounds. A wound, on the other hand, might be penetrating as well as perforating. A gunshot hitting the head may pass through the cranium and brain before resting under the scalp, resulting in a penetrating head injury but a puncturing wound to the skull and brain.

These wounds can be divided into four broad categories, depending on the range from the muzzle to target:

Contact Injuries

The muzzle of the pistol is maintained against the surface of the body during discharge in contact wounds. Hard, loose, angled, or incomplete contact wounds are common (a variation of angled).

Hard Contact Wound

The muzzle of the handgun is pressed “hard” against the skin in hard-contact wounds, causing the skin to surround the muzzle. The direct edges of the entrance are burned by the flaming gases of ignition and darkened by the soot in hard contact wounds. This soot is embedded in the burnt skin and cannot be completely removed by washing.

Loose – Contact Wounds

The muzzle is kept casually on the skin in loose-contact wounds, and the gas traveling previous to the bullet, as well as the bullet itself, indents the skin, creating a temporary space between the skin and the muzzle through which gas can leak. The soot carried by the gas is deposited in a region around the entry. There is no need to be concerned about this soot being washed away. A few unburned grains of powder may also leak through this gap and deposit on the skin in the soot region.

Angled – Contact Wounds

The barrel is held at an acute angle to the skin in angled-contact wounds, such that the entire circumference of the muzzle is not in contact with the skin’s surface.

Incomplete Contact Wounds

Angled-contact wounds are a type of incomplete-contact wound. The weapon’s muzzle is kept against the skin in these, however, there is an opening between the muzzle and the skin because the body surface is not completely flat.

Near Contact Injuries

Injuries sustained near contact occur in between contact and intermediate-range wounds. It is difficult to tell the difference between near- and loose-contact injuries because their appearances are similar.

The weapon’s muzzle is not in contact with the skin in near-contact wounds because it is held a short distance away. However, because the distance is so short, the powder grains emerging from the muzzle do not have a chance to scatter and mark the skin, resulting in the powder tattooing that intermediate-range wounds require.

There is an entrance wound in near-contact wounds, which is surrounded by a large zone of powder soot covering burnt, blackened skin. The scorching zone is larger than that of a loose contact wound.

Intermediate-Range Injuries

An intermediate-range gunshot injury occurs when the weapon’s muzzle is held away from the body at the time of discharge yet close enough to cause “powder tattooing” of the skin from powder grains ejected from the muzzle along with the bullet. The presence of these patterns is a prerequisite for intermediate-range gunshot wounds. Microscopic sections of the entrance hole in intermediate-range wounds should show grains of powder embedded in the skin adjacent to the entrance hole.

Distant Wound

The only marks on the target in distant wounds are those which are made by the bullet’s mechanical action in puncturing the skin. A stellate or asymmetrical aspect to distant gunshot wounds in the head can resemble a contact wound. Both pistols and rifled bullets show this phenomenon.

Exit Wound

An exit wound is recognized by the absence of carious marks found around the entrance wound such as the presence of averted edges of the skin and the shape and size of the wound.

Exit Wounds are produced by the penetration of a bullet traveling through the body and moving out of it. Exit wounds are typically larger than entry wounds because the round decelerates and shatters within the tissue and surrounding muscle as it passes through the victim’s body. The projectile’s slowing means that as it approaches the conclusion of its trajectory, it must exert more force to push through. As a result, the exit wound usually appears to be larger and more destructive than the entrance wound. The bleeding is much more marked at the wound of exit.

Shotgun Injuries

Wounds are produced by shotguns or smooth bored firearms. These wounds differ from those of other missiles because the spectrum of wound severity is large. After all, the pellets scatter as they travel. A shotgun when fired discharges the components such as gun flame, gun smoke containing soot particles and gun powder particles, gases, and lead shot.

Rifled Firearm Injuries

On firing a gun, several components emerge out along with the bullet. The components, which are ejected on firing, are the bullet, smoke, which contains soot particles, unburnt gun powder particles, and hot combustion gases, and gun flame. Though the bullet is responsible for the injury produced, each of the other components in the firing discharge can also impart certain specific effects depending on the range of firing.

Pink Coloration

If a shot is fired from a very close range or in contact with the skin, some carbon monoxide (produced in the combustion of propellants) gets absorbed in the skin and flesh. It gives a pink coloration to the skin around the wound which indicates firearm injury and injury from a close range.

Charring/ Scorching/ Burning/ Singeing

These are the impacts of flame or hot gases created during propellant combustion.

When a shot is fired from a very close range, it causes charring. The firearm and range are defined by their size, shape, and range. Blackening, Tattooing, Dirt Ring and even Contusion Ring are all terms used interchangeably to describe the Charring. The Charring is different from Blackening. The latter can be removed with a cotton swab moistened with spirit while the former cannot be removed in this way.

Blackening

The blackening is caused by smoke deposits. The smoke particles are light. They do not travel far. Therefore, smoke deposit i.e. blackening is limited to a short-range. Smoke is light grey to dark grey in black powder. It is grey to black in smokeless powder. The size of the powder soot blackening expands as the distance between the muzzle and the target increases, while the density decreases.

Tattooing

Tattooing is often referred to as stippling or peppering. It’s the accumulation of unburned or partially burned powder particles beneath the skin. Normally, tattooing cannot be removed with a wash. Tattooing is an antemortem phenomenon that shows the person was alive when he was shot.

Even though the powder may leave marks on the skin if the person was dead before being shot. These marks have a moist grey or yellow appearance rather than the reddish-brown to the orange-red coloration of an antemortem injury.

Dirt Ring or Projectile Wipe Ring

Some projectile deposits a dirt ring around the wound. The projectile may have grease on it. The dirt collects on the grease, which then deposits itself around the wound. On the bullet, there is a soot/GSR deposit.

The soot/GSR is picked up by the projectiles from the powder ejecta that rushes past them inside or outside the barrel. Dirt can come from intermediate targets such as clothing, mud walls, the surface where the projectile ricocheted. The pellets and buck shots are rubbed with graphite in the shotgun ammunition. The projectiles carry a small amount of graphite, which they deposit around the entry hole. The entry wound’s edges may also become blackened as a result of the lead bullets.

Contusion

The edges of the wound are contused by the impact of the projectile. The color of contusion varies from reddish dark to bluish-black. Contusions frequently take the shape of a band around the wound and are of constant width. The tissues are swelled and ruptured.

Muzzle Impression

Muzzle Impression is the annular skin impression against the muzzle caused by discharged gases or the creation of a temporary cavity in contact and near contact gunshot wounds. Muzzle impression can be detected in “shored” exit wounds, but not in normal exit wounds. Because of the greater gas volume produced by the large cartridge, muzzle imprints are far more common than in wounds from the Short cartridge.

Grazing Shots

A grazing shot is one in which the bullet passes along the surface of the body without penetrating. Injury to the surface of the body is generally limited to the skin itself and the subcutaneous connective tissue.

However, depending on the area of the body and the thickness of the fatty tissue, the subcutaneous fatty tissue, as well as the higher layers of muscle, may be affected.

The defect that results is frequently in the form of a channel with abraded tissue. The shorter the area of contact between projectile and skin, the smaller and more insignificant-looking such a graze is likely to be. It’s impossible to tell which direction the projectile was traveling in the graze wounds.

Abrasion Ring

The abrasion ring is characterized by a reddish-brown color surrounding the entrance hole. Generally, fresh entrance wounds have a fleshy appearance and also have an abrasion ring with a moist. The abrasion ring is produced, when a projectile scours the hole as it depresses and perforates the skin. The width of the abrasion ring varies based on the firearm’s caliber and the angle at which the projectile entered the body.

Tandem Bullet Effect

This is especially important if a weak, old, or unused firearm is discharged without cleaning the barrel. Every potential exists that the bullet shot earlier did not eject from the barrel, but rather remained lodged in the barrel itself, and was simply carried away in the course of a second firearm discharge, together with the bullet fired again. Both get lodged together into the wound of entry, arranged exactly one behind the other in a row.

Frangible Bullet Effect

Its effect is an inferior bullet, which on penetrating the body gets broken up into several fragments and produces severe injuries, by each fragment. The majority of them are made of lead or iron. It’s difficult to recover and match a test bullet. When a frangible bullet hits a solid surface, such as a steel plate or a backstop, it breaks completely, disintegrating into small pieces.

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