Firearm Injuries: Entry, Exit, Range and Pattern

The foundational division is smooth-bore versus rifled. A shotgun and a country-made katta have unrifled, smooth interiors; they fire pellets, shot, or in the country-made case whatever the maker has loaded into a paper cartridge. A rifle or handgun has a rifled bore that imparts spin to a single bullet for gyroscopic stability. The rifling produces the land-and-groove marks that the FSL ballistics division reads off the recovered projectile.

• Smooth-bore weapons fire shot at low to moderate pressure. Wound pattern depends heavily on range because the shot spreads as it travels.
• Rifled weapons fire a single, spinning bullet at high pressure. Wound pattern at the skin is more uniform with range; the range cues come from the muzzle effects (soot, tattooing) rather than from projectile dispersion.
• Country-made firearms are usually smooth-bore single-shots, but loadings vary wildly. Cases have recovered cartridges filled with bicycle ball-bearings, cut nails, broken glass and even gravel mixed with black powder.

A modern centre-fire cartridge has four parts and each part is forensic evidence in a different way. Identify the parts on a recovered round and you can already say something about the weapon that fired it.

• Case: the brass or steel cylinder that holds everything else. After firing, the ejected case carries breech-face marks, firing-pin impressions, extractor scrapes and ejector marks. These are individual-characteristic marks an FSL examiner can match to a suspect weapon.
• Primer: the small impact-sensitive cup at the base. Struck by the firing pin, it ignites the propellant. Primer residue (lead styphnate, antimony sulfide, barium nitrate) is the main source of the Sb-Ba-Pb signature that defines GSR.
• Propellant: the smokeless powder grains that combust to produce expanding gas. Unburnt grains driven into the skin produce tattooing. Burnt grains and soot produce blackening.
• Projectile: the bullet (rifled cartridge) or shot column (shotgun cartridge). The bullet recovered from the body or the scene carries land-and-groove marks read against the suspect weapon's test-fire.

In country-made cases the cartridge is often a re-loaded shotgun shell with paper wadding, mixed shot and black powder. The paper wad recovered from the wound is itself evidence; it carries powder residue, matches the loader's pattern, and sometimes carries newspaper print that can be tied to a region.

1. Locate the projectile
   Bullet in tissue, pellets within track, or shot column at depth. For shotguns, count the pellets recovered and compare against a known load.
2. Locate the case (if applicable)
   Search the scene in expanding arcs from the suspected firing position. Note the eject direction relative to weapon type.
3. Locate wadding and shot cup
   Plastic shot cup and paper wad are routinely missed; they sit either inside the wound or just beyond it on through-and-through shots.
4. Photograph in situ, package separately
   Each item in its own paper envelope. Bullets and pellets are not stored in glass or plastic that abrades surface marks.
5. Forward to ballistics with the suspect weapon
   FSL ballistics division performs test-fires into water tank or cotton box, then compares bullet and case markings under comparison microscope.

The entry wound carries the range cues a forensic pathologist is trained to read. Four canonical brackets, each with characteristic skin findings.

Contact shot. Muzzle pressed against the skin at firing. Expanding gas drives into the wound and back-pressures into the surrounding tissue, producing several distinctive signs:

• Muzzle imprint (barrel impression). A patterned abrasion that mirrors the shape of the muzzle and front sight. A muzzle imprint is direct proof of contact.
• Stellate (star-shaped) tear. Expanding gas under the skin tears the wound margins outward in a radiating, often four- to six-point star. Especially common over bone (skull, sternum) where the gas can't dissipate sideways.
• Soot deposition deep in the wound track. Soot is driven into the wound channel itself, not just on the surface.
• Pink coloration of tissues. Carbon monoxide in the muzzle gas binds to local haemoglobin and myoglobin, producing a cherry-pink colour of muscle and underlying tissue along the early track.
• Abrasion collar present. As with all entry wounds; the muzzle imprint surrounds and extends beyond it.

Close shot (roughly 0 to 15 cm). Muzzle near but not touching the skin. Soot is the dominant sign, with tattooing layered over it:

• Soot blackening on the skin around the entry, a few centimetres in diameter, wipeable in part.
• Tattooing (punctate, non-wipeable) under or beyond the soot ring.
• No muzzle imprint and usually no stellate tear.

Intermediate shot (roughly 15 to 60 cm). Soot does not reach the skin but unburnt powder grains do.

• Tattooing without soot is the hallmark of the intermediate range bracket.
• Abrasion collar present, as on all entries.
• Tattoo spread widens with range; at the far end, individual specks may be 5 to 8 cm from the wound.

Distant shot (beyond 60 cm). Neither soot nor unburnt powder reaches the skin.

• Abrasion collar only. Clean, circular entry with a circumferential ring of dried, slightly depressed grazed skin.
• No soot, no tattooing. Range cues from the skin are exhausted; range estimation moves to projectile recovery and scene geometry.

Exit wounds carry no range cues. They document trajectory: where the bullet travelled after entering, what structures it traversed, and the wound geometry at the far side of the body. Four features reliably distinguish exit from entry.

• Larger than entry, usually. The bullet yaws and deforms as it passes through tissue. By the time it reaches the exit skin it is wider, may be tumbling, and may have picked up bone fragments acting as secondary projectiles. The exit hole is bigger and more irregular.
• No abrasion collar. The skin at exit is pushed outward, not scraped inward. The classical circumferential ring of grazed skin is absent. A "shored exit" against a hard surface (wall, floor, belt buckle) can mimic an abrasion collar; this is one of the few exceptions a pathologist must flag.
• No soot, no tattooing. Range residues are deposited at the muzzle end, not the exit end. Their absence at exit is diagnostic.
• Slit-like or stellate shape. Over thin skin areas with bone close beneath, the exit may be a clean slit or radiate into a stellate tear from internal pressure.

Track analysis is the connective tissue between entry and exit. The pathologist documents the direction of fire (front-to-back, left-to-right, downward, etc.), the organs and structures along the track, the type of internal damage at each, and any deflections off bone. Direction of fire becomes critical when the scene reconstruction is being built against a suspect's account. A claimed self-defence shot from below upward, with an actual track running downward through the body, is a reconstruction inconsistency that breaks the suspect's story.

Shotgun and rifled-weapon wounds require separate analytical frameworks beyond roughly 60 cm. Pellet dispersion provides range information for shotguns where muzzle effects cannot; rifling marks identify the weapon type and individual barrel for rifled weapons where pellet dispersion is irrelevant.

Shotgun-specific patterns. A 12-gauge shotgun firing No. 6 birdshot from contact range produces a single round hole roughly the size of the bore (about 18 mm). As range increases, the pellets spread according to choke and load. A rough teaching rule on Indian shotgun loads is that the pellet spread diameter at the target equals about 1.5 cm per metre of range at close to intermediate distances, with choke and load type modifying the slope. At 1 to 3 metres the entry is a central hole surrounded by satellite pellet wounds. Beyond 3 to 4 metres the pellets arrive as a loose pattern with no central hole. The shot cup and wadding behave differently and can land short of the body or stay in the wound; their location is part of the range estimate.

Rifled-firearm specifics. A recovered bullet carries class characteristics: the number, width and twist direction of lands and grooves, and the twist rate (e.g. 1:10, 1:14). These are matched against a database of known weapons to narrow the suspect weapon type. The actual one-to-one match comes from individual marks: microscopic striations from imperfections in the bore, and on the cartridge case, breech-face and firing-pin impressions. The CFSL Chandigarh and CFSL Kolkata ballistics divisions, and the major state FSLs at Mumbai, Chennai and Lucknow, have comparison-microscope workflows and IBIS-equivalent reference setups for these matches.

1. Estimate range from skin signs
   Apply the four-bracket scheme: contact, close, intermediate, distant. Note shotgun pellet spread separately if applicable.
2. Recover all projectiles
   Bullet, pellets, shot cup, wadding. Each in a separate paper envelope; do not use metal forceps.
3. Recover ejected cases at scene
   Critical for rifled-weapon individual matching. Smooth-bore casings less informative but still preserved.
4. Forward with the suspect weapon
   Ballistics division test-fires the suspect weapon under controlled conditions and compares marks under a comparison microscope.
5. Range-confirm with test-firing
   If the wound suggests close range, the suspect weapon is test-fired at the estimated distance against witness panels (paper, fabric) and the spread is matched.

Three topics remain: gunshot residue collection, medico-legal differentiation of manner of death, and the packaging discipline required to get a recovered bullet into court.

Gunshot residue (GSR). When a firearm discharges, microscopic particles of primer residue (antimony, barium, lead) and burnt propellant escape from the breech, muzzle and any gaps in the cylinder or action. They settle on the shooter's web of the hand, dorsum of the hand, face, hair and clothing. GSR is collected with adhesive carbon stubs or wet swabs and analysed by scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDX). The signature particle is a roughly spherical Sb-Ba-Pb fused particle; finding even a few is highly indicative of recent discharge.

• Presence is not proof of shooter. GSR transfers from handcuffs, police vehicles, a hand handled by another contaminated hand, or simply standing next to a shooter. Indian appellate jurisprudence is cautious about treating GSR as more than corroborative.
• Absence is not proof of innocence. GSR is lost rapidly to hand-washing, sweating, and even brushing against clothing. A 4 to 6 hour window from discharge to sampling is the rough field guide.
• Collection sequence matters. Hands first (right, then left), then face, then clothing; each in its own sealed packet, labelled and forwarded to the FSL ballistics or chemistry section.

Medico-legal differentiation of manner of death.

Bullet recovery and forwarding. In Indian practice this is governed by the same sealed-packet protocol that applies to all physical evidence, with two firearm-specific tightenings:

• Each projectile, case, wad and shot cup in its own paper packet. Metal-on-metal contact within a single packet is reason enough for the defence to challenge the recovered striations.
• The seal is signed by the post-mortem doctor and counter-signed by the area magistrate where the autopsy is conducted. The magistrate's signature on the seal is the audit hook that distinguishes a forensically recovered bullet from one allegedly inserted into the chain later.

Bullet forwarding ties this topic back to the broader handling discipline covered in Processing Physical Evidence at the Scene and the documentary integrity covered in Chain of Custody. The autopsy work itself is covered in Autopsy and Post-Mortem Examination.