Gunshot wound from revolvers and Automatic Pistols are of different types.
They may be classified on the distance of the muzzle of a firearm from the body; contact, close, near and distant. The flame extends up to 8 cm; smoke up to 30 cm. and unburnt and partially burnt powder grains and small metallic particles up to 60 to 100 cm in case of rifle and 40 to 75 cm. with handguns.
The amounts of smoke, flame and powder grains and the distances to which they will be carried will vary depending upon the type of gun powder used, the amount of powder load, the size and weight of the projectile, the tightness of fit between the projectile and gun barrel and the type of firearm. Silencers will filter out a great proportion of soot and powder particles due to which the range appears greater than it actually was
In firm or hard contact (muzzle pushed hard against the skin), the resulting one is similar to that from a shotgun. In some contact wounds, the imprint of the muzzle of the gun is found as patterned abrasion on the skin around the gunshot wound.
This results from the great distension of the subcutaneous tissues from the entry of gases which forces the surface against the muzzle. The mark may be an incomplete, indistinct bruise and occasionally a perfect imprint of the muzzle.
Many muzzle impressions are not recorded due to the rapid removal of the weapon by recoil. When a firearm is fired, the shooter gets a jerk on the shoulder or wrist due to recoil movement of firearm.
The discharge from the muzzle, i.e. gases, flame, powder, smoke and metallic particles are blown into the track taken by the bullet through the body. The one is large and triangular, stellate, cruciate or elliptic shows cavitation due to the expansion of the liberated gases in the skin and tissues, which show laceration. The margins are contused and averted due to gases coming out of the entering gunshot wound under pressure.
Singeing of the hair may be present due to the escape of hot gases by the sides of the muzzle end. The area immediately around the perforation is abraded, and this thin rim of abrasion is usually covered with powder residue. Tattooing begins when the muzzle to target distance exceeds one cm.
In firm contact with the skin where the bone is not shallowly situated, the ever expanding gas continues to penetrate deeper, to be scattered in the soft tissues of the body. The one is not eruptive or explosive in appearance.
In contact shot, the muzzle blast and the negative pressure in the barrel following discharge may suck blood, hair, fragments of tissues and cloth fibres several cm. back inside the barrel called “back spatter”. Back spatter is more common with shotgun.
Sometimes, blood may soil the hand of the person firing the gun. In loose contact or near contact, some of the gases escape with the resulting scattering of the muzzle blast and an unusual arrangement of soot is seen on the skin known as corona.
The corona consists of a circular zone of soot deposit surrounding the bullet defect, but separated from it by a band of skin without a deposit of soot. This is due to the gas expanding about the muzzle, first at a velocity too high to allow for the settling out of soot, with a subsequent loss in velocity at a short distance from the muzzle, allowing the soot to finally deposit on the skin.
Gunshot wound has clear margin, inverted, abraded and surrounded by soot. The blast effect is not as marked as in tight contact, and splitting of the gunshot wound edges does not occur.
Evidence of burning is noted on microscopic examination in the edges of the contact and near- contact bullet wounds due to the flame of muzzle blast. Singeing of the hair may also be seen. The discharge from the muzzle, i.e., gases, flame, powder, smoke, and metallic particles are blown into the track taken by the bullet (projectile or missile) through the body. The powder residue is usually grossly visible in the subcutaneous and deeper areas.
The entrance track is blackened by powder and smoke and seared and charred by flame. In loose contact gas and soot escape from the side of the barrel, causing an eccentric area of burning and blackening.
Head gunshot wounds appear, as very large explosive type of injury with bursting fractures. The skin one is large and irregular because of the expansion of gases between the scalp and the skull which causes aversion and splitting of the skin at the margins of the entrance gunshot wound.
This results in undermined, ragged, stellate, triradiate or cruciform opening with averted margins from which tears radiate. The tearing may be severe, as the gas raises a large dome under the skin which then ruptures.
Such are usually produced by large calibered pistols. A subcutaneous pocket containing blood mixed with gunpowder is formed by separation of the tissues. When a small calibered pistol is used, it may be small and regular. Soot may be deposited on the bone surrounding the hole. This should not be mistaken for lead rubbed off on the bone during the passage of the bullet, which is seen only in a localized area.
Frequently, soot passes deeper into the gunshot wound track and a faint gray or black discoloration may be seen on the inner surfaces of the skull around the hole and on the dura mater. Fissured fractures often radiate from the circular defect due to the considerable sudden expansion resulting from the muzzle blast. Fractures of the orbital roofs occur due to the same mechanism, but the dura over the orbits is usually not damaged.
A bullet traveling the cranial cavity destroys the structures in its pathway and produces an expansile or explosive effect. A bullet fired from a short distance may produce an explosive effect sufficient to burst the scalp, shatter the skull and dislodge the brain.
In less severe type of injury, a cone of damaged cerebral tissue is seen surrounding the gunshot wound track. When it moves through the body, it transfers kinetic energy to the surrounding tissue, which is thrown forcefully away from the path in a radial manner, and a temporary cavity is formed in its path.
The margins of entry, subcutaneous tissues and muscles around the track of the bullet may be bright pink due to the presence of CO. Abdominal gunshot wounds show cavitation because of the blast effect.
When the part is clothed, the hole in the cloth touching the muzzle is sometimes surrounded by a flat ring corresponding to the outline of the muzzle. The loose fibers of the cloth in the center of the hole are often turned outward due to the expanding gases returning through the defect. These fibers are usually blackened by smoke. In synthetic fabrics, melting of the ends of these fibers may be observed sometimes.
Varying amounts of soot is deposited on the edges of the hole. If the clothes are bloodstained, deposits of soot may not be recognized, but the inside of the garment may show large deposit of smoke. This is due to the spreading of smoke by the muzzle blast between the skin and the clothing and is seen commonly if it passes through several layers of material.
Each layer is blackened on both sides of the fabric, but the skin gunshot wound does not show blackening or tattooing. If there is no intervening clothing, the smoke passes into it but a small amount is deposited on the edges, especially if contact with the muzzle was loose. Fine granules of powder and deposits of soot can be demonstrated in the depth by a layer wise dissection of the injury.
This term is applied when the victim is within the range of the flame, i.e., 5 to 8 cm. The term ‘point blank’ is used when the range is very close to or in contact with the surface of the skin. The entrance gunshot wound is circular with inverted edges, but the rebounding gases may level up or even evert the margins.
The skin is burnt with singeing of the hair. The one surrounding it is hyperaemic and shows some bruising, burning, blackening and tattooing. The palms and soles are very resistant to powder tattooing.
The blackening can be wiped off the skin by a wet cloth, but the tattooing cannot be wiped off. Carboxyhaemoglobin will be present in the gunshot wound track in diminishing concentrations up to 30 cm.
The length of the barrel of a firearm has considerable effect on the spread of smoke produced on the target, e.g., a gun with a 5 cm. barrel will spread the smoke over a much larger area than a weapon having a 15 cm. barrel, fired from the same distance and using the same type of ammunition.
Usually, as the distance between the muzzle and the target increases, the pattern of soot or powder on the target increase in diameter and the density of particle deposition decreases. In handguns, up to 15 cm. from the muzzle, abundant gunpowder and diminishing amount of soot are deposited on the target.
Hair in the surrounding area may be clubbed, swollen at intervals by heat, or burnt. Abraded collar and grease or dirt collar are present. Between 30 cm. to one metre there is no burning and blackening, but some amount of tattooing is usually seen. The internal injuries are almost same as in the case of contact.
This term is applied when the victim is within the range of powder deposition, and outside the range of flame, i.e., up to 90 cm. If the discharge occurs at a distance of about 15 cm., the lacerating and burning effects of gases are usually lost due to the dispersion cooling of the gases before they reach the skin.
The entrance gunshot wound is seen as a round hole, slightly smaller than the diameter of the bullet, due to elasticity of the skin, with a bruised and inverted margin and a zone of blackening and tattooing.
The individual tattoos are caused by the individual unburned powder grains being blown into skin. A small magenta-colored zone, an actual micro-contusion is seen surrounding each tattoo point, which is caused by the trauma of the high speed impaction of the powder grain with rupture of small blood vessels and resulting minute hemorrhage. If the bullet strikes the body at an angle, blackening has a pear- shaped area, with the larger area on the side nearer the barrel.
As the distance increases, the intensity decreases and blackening and tattooing is spread out over a large area, and there is no singeing of the skin. Abrasion and grease collar are present. Occasionally, when the range of fire is short, small fragments of metal derived from the interior of the barrel of the gun or the bullet itself, are embedded in the skin in the vicinity of the entrance gunshot wound.
Distant Shot (Above one meter)
The entrance gunshot wound is smaller than the missile due to the elasticity of the skin, circular, and margins are inverted. Distant entrance ones of the palms and soles are irregular, often having a stellate appearance, without an abrasion ring, and look like exit. Burning, blackening and tattooing are not seen. The skin adjacent to the hole shows two zones, the inner of grease collar and the outer of abraded collar.
In case of semi-jacketed bullet, the jacket separates as it goes through the body, and the core mushrooms into small pieces. X-ray gives a picture of “lead snowstorm”. If a semi-jacketed bullet passes through an intermediary target, the jacket may separate from the core, and both missiles may penetrate the body.
When it passes through an intermediary target, such as glass, may cause superficial lacerations around the entry gunshot wound and these are referred to as pseudo-tattooing, which are larger and more irregular than that caused by powder. The caliber of it cannot be determined, if it strikes the skin surface obliquely.
Stretching and cavitation and dissipation of kinetic energy are the major causes of the lethal effects of it, together with deformation and fragmentation.
The Abrasion Collar (marginal abrasion)
As the bullet strikes the skin, it first indents and then stretches its surface, so that perforation takes place through a tense area. After it has perforated, the elasticity of it causes the skin defect to contract. It is abraded (abrasion collar) around the hole due to rubbing of the gyrating body of it against the inverted epidermis and heat of it.
A black colored ring “grease or dirt collar” (wipe soiling) is seen as a narrow ring of skin, lining the defect, and is sharply outlined. This is caused from the removal of substances from the bullet as it passes through it, i.e., bullet lubrication, gun oil from the interior of the barrel, lead from the surface of the bullet, barrel debris, etc. It is more marked in a distant. Infrared photography clearly indicates the presence of black ring around the hole.
Dirt collar is less common if the it is jacketed. By contrast, soot is dark in the center and fades towards the periphery. The abrasion collar surrounds the dirt collar. The abraded collar is reddish at first, but becomes reddish brown as it dries.
Some contusion is present in abraded collar, and as such, it is also called “contusion collar”. These two features are proof of an entrance gunshot wound. Irregular and occasionally patterned abrasion collar is sometimes produced by coarse article of clothing scraping on the skin.
Abrasion collar may be absent when the tissues are soft and yielding, e.g. in the abdomen or buttocks. It may also be absent, especially where skin is taut, and in some high velocity gunshot wounds. In addition to abrasion collar, there is often a slightly wide circle of peeled keratin, where the stratum corner of the skin is raised to form a slightly frayed edge around the entry.
In the skull, entrance shows a punched-in (clean) hole in the outer table. The inner table is unsupported and a cone-shaped piece of bone is detached forming a crater that is larger than the hole on the outer table, and shows beveling (sloping surface). Fissured fractures often radiate from the defect.
As the bone fragments have to pass through the dura before entering the brain, lacerations are usually irregular and involve leptomeninges. Pieces of bone from gunshot wound of entrance are often driven into the cranial cavity and may establish the bullet track.
Pieces of bone may produce short accessory gunshot wound tracks. At the point of exit, a punched-out opening is produced in the inner table and beveled opening on the outer table.
Beveling is produced when the unsupported diploe everts and fragments on the side where the bullet leaves, this in contrast to the approach side where the rim of the defect is supported by the underlying bone.
The exit is larger due to the deformity and tumbling of it after entering the skull. There are often fissured, sometimes comminuted fractures radiating from the central hole. Asymmetry of the beveling is useful in assessing the angle of fire.
The same appearance is seen in sternum, pelvis, ribs, dentures and thumbnails.
It can determine the sequence of fire, when several bullets have struck the cranium. This rule is applicable to any multiple blunt force, causing skull fractures. This rule has been developed by Madea in relation to bullet injuries.
The test depends on the observations of the fracture lines either when they intersect each other, or when they intersect a cratered lesion, so that one can determine which crack or defect must have been formed first.
If it strikes the body at right angle, the abrasion collar is circular and uniform because the scraping by it is equal on all sides of the gunshot wound. If it strikes the body at an angle, the gunshot wound itself is round, but the marginal abrasion is oval or elliptical, due to increased width on the side from which it comes, due to it moving across a wider surface of the skin on that side.
The direction of the it is from the wide to the narrow side. Oblique angle will cause an elliptical mark, the length of which increases as the angle decreases. When it enters the body from an oblique angle, one edge of the gunshot wound is shelved or undercut, which indicates the direction from which it entered. Shelving is usually seen in the deeper layers of the skin rather than in the tissues below.
THE WOUNDING POWER OF BULLETS
The size and velocity of the it are the two most important factors. The power of it is proportional to its mass, multiplied by the square of its velocity. Another factor is the density of the tissue, e.g., destruction is greater in dense tissue such as bone than in soft tissues. The tissues show considerable damage due to the wobbling of it within the body.
A bullet traveling at high velocity produces a clean, circular punched-out aperture or slit and usually perforates the body. It is not deviated from its path by striking a bone, but may cause its comminution or splintering. A bullet of low velocity causes contusion and laceration of the margins.
It is easily deviated and deformed by striking some hard object, and often lodges in the body. Large ones cause greater damage than small ones. Round ones produce larger gunshot wounds than conical ones. A bullet of smaller size than the caliber of the weapon may cause only bruising.
If it is through a clothed surface, examination of clothing only can indicate its range. In a contact one, the clothing usually shows a cross-shaped perforation, and the skin around the bullet hole and the deeper layers of the cloth are blackened.
In close ones, the clothing may absorb or filter out all of the products of discharge except it. An entrance hole in clothing, if made by a lead or full metal-jacketed bullet, may produce a grey to black rim known as “bullet wipe” (grease, soot or debris from the barrel of the gun). Sometimes, pieces of cloth are carried into the gunshot wound of entrance.
If the fragments on impact, an exit may not occur. It may be reduced to granules, and there may be difficulty to remove them from the body, even when identified by X-ray. Full metal-jacketed bullets usually exit un-deformed. Exit may vary considerably in size and shape.
They may be round, stellate, cruciate, elliptical, crescent-shaped. An exit produced by a tumbling bullet or with one passing sideways through the tissues may be elongated or slit-like resembling a stab, incised or lacerated gunshot wound.
The same appearance may be seen in a part of the body in which the skin folds or changes direction, e.g. in the buttock crease, under the arm, or in the groin or umbilical area. Exit wounds of the head are usually star-shaped resembling contact entrance. In some cases, the entrance and exit may look alike. The exit is of help in determining:
When the weapon has been fired in contact with the bone or at very close range, the exit is usually smaller than the gunshot wound of entrance. With increased range, the exit is larger than the gunshot wound of entrance. With high velocity bullet, the two may be of the same size.
The edges of the exit may be puckered or torn and averted and pieces of contused, hemorrhagic subcutaneous fat may protrude through the defect. The edges are free from signs of burning, blackening or tattooing and there is no contusion or abrasion collar.
If the skin at the exit is firmly supported, the exit appears as a circular or nearly circular defect surrounded by a margin of abrasion (usually broader than that of entry), resembling a gunshot wound of entrance (shored or supported exit).
The shored type of exit caused by a bullet fired at long range or through clothing, or when the firearm is of small caliber and discharged in contact with the skin at a point where bone is not immediately below the surface, resembles gunshot wound of entry.
Many shored exit are caused if a firm object, e.g., a belt, the waist band of trousers, etc., brassiere, collar and tie, is pressed against the body at the site of exit, or if the body is leaning against a hard surface such as a wall, back of a chair or the floor, door, car seat, mattress, bedding, or if the person was lying down.
In such cases the skin, crushed by the exiting bullet, produces an irregular, lopsided and large abrasion around or adjacent to the gunshot wound (shored’ exit).
In a fatty person, the edges of both the gunshot wounds of entrance and exit may be averted due to protrusion of fat. They may also be averted in decomposed bodies. The variation in the shape and large size of exit are due to:
Rarely, slit-like exit wounds are seen probably due to the deformity of it, caused by impact of it on bone during its passage through the body. Such gunshot wounds are mostly seen on the head and over the shoulders. Occasionally, it may be found protruding from an exit. In incomplete exit, it lacerates the skin but is trapped and lodged within wound.
Entry may be larger than exit due to:
Revolvers and automatic pistols cause similar gunshot wounds, but penetrating power of bullets of pistols is much greater because of the greater velocity and because of their being coated with hard metal.