Firearm Wounds

Medicolegal view

Objectives:

To know the following

definition and classification of wounds
the type of trauma and wounds of medico-legal importance
factors affecting the wound
estimate the date of wound occurrence
different types of wounds
complications of wounds

Firearm

“An instrument or device with which it is possible to propel a projectile by means of the expansive force of the gases generated by the combustion of an explosive substance”

Revolver

S&w 40XvK Magnum

Pistol

The image presents a collection of various pistols, showcasing different types and designs. The pistols are displayed in a images format, with each image highlighting a unique aspect of the firearms.

The top-left image features a semi-automatic pistol with a silver finish and a brown grip, set against a red background.
The top-right image displays a Derringer-style pistol with a silver finish and a black grip, positioned on a beige surface.
The bottom-left image presents two antique pistols:
- Flintlock Pistol: An older design with a brown handle and silver accents.
- Percussionlock Pistol: Another antique design with a brown handle and silver accents.
The bottom-right image showcases a modern pistol with a black finish and a tactical accessory attached to the barrel, set against a dark blue background.

The image provides a visual representation of the evolution and diversity of pistol designs, from historical to modern times.

Rifle

The component of firearm:

Parts of a Rifle

Receiver
Bolt
Rear Sight
Front Sight
Stock handle of firearm
Trigger
Safety helps to prevent accidental firing
Trigger Guard (housing)
Magazine
Barrel Metal tube that Projectile Travels Through

Parts of a Handgun

Pistol & Revolver

Pistol:
- Rear Sight
- Slide Stop
- Barrel
- Front Sight
- Muzzle
- Grip Safety
- Magazine Release
- Trigger
- Trigger Guard
- Grip
- Magazine
Revolver:
- Muzzle
- Cylinder
- Barrel
- Hammer
- Trigger

Parts of a Shotgun

Stock
Safety Mechanism
Breech Bolt
Receiver
Trigger Guard (housing)
Trigger
Ejection Port
Fore-End or forestock
Magazine Cap
Barrel
Muzzle
Front Sight

Ballistics

THEORETICAL
- Interior ballistics
- Exterior ballistics

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PRACTICAL
- Wound ballistics
- Clear Concept

INTERIOR BALLISTICS

Knowledge of the forces responsible for propulsion of projectile within the bore of the barrel till the end of the projectile.

Firearm Design

Grip
Action
Barrel
Barrel
Action
Grip or Butt Stock

Classification of Firearms

Classified on the basis of barrel

Barrel
- Steel tube for jetting of the projectile. Two ends --- Breach & Muzzle end
Bore
- Internal diameter of the barrel. May be SMOOTH or RIFLED

Ammunition Design

Projectile consists of:-

Cartridge Case
Primer
Powder charge (Black or Smokeless)
Plastic Wad
Shot charge (Bullet or Lead shots)

CARTRIDGE CASE

Function: expands and seals chamber against rearward escape of gases.

Composition: usually brass (70% copper 30% zinc); also plastic and paper in shotgun shell tubes.

Shape:

(a) straight (“always” pistol ammunition)
(b) bottleneck (“always” rifle ammunition)
(c) tapered (“obsolete”).

Headstamp: manufacturers identification imprinted or embossed on cartridge case.

Primer

The major primer elements are Lead styphnate(Pb), Barium nitrate (Ba), or a Antimony sulphide(Sb). Usually, all three are .present Less common elements include Aluminum (Al), Sulfur (S), Tin .(Sn), Calcium (Ca), Potassium (K), Chlorine (Cl), or Silicon (Si) Primer elements may be easier to detect in residues because they do not get as hot as the powder, and compounds (not just elements) may be detectable. (Tassa et al, 1982b)

Various types of Ammunition

HANDGUN

.45 ACP
9mm
.38 Special
.224 BOZ

RIFLE

FN SS-190 5.7mm
5.56mm
7.62mm

Chain of Events

Strike
Primer ignites
Powder charge burns
Temperature increases
Gases produce
Chamber pressure increases
Bullet/Shot charge moves
Exit of bullet
Chamber pressure zero

Gases produced: Carbon dioxide, Carbon monoxide Nitrogen, Sulphurated hydrogen

Exterior Ballistics

Knowledge of forces acting on the shot while it “leaves the barrel till it reaches the target”

Velocity of bullet at the muzzle end for various firearms: i. Revolver:- 600 - 900ft/sec ii. Pistol:- 1200 - 1440 ft/sec iii. Rifle:- 2000 - 3500 ft/sec
Forces present in the medium a. Air resistance b. Gravity

Mechanism of Wound production

Laceration & Crushing
- Shock waves
- Cavitation

Laceration & Crushing

—— produced by the direct effect of bullet

SHOCK WAVES

Types of cavitations

Temporary:
Permanent:

Cavitation … created by the bullets travelling at speeds > 1000 ft/sec Size & shape depends upon the capacity of the bullet to disperse energy in the surrounding tissues

Effects of Cavitation

Stretches & damages smaller blood vessles, nerves & even bones

Figure 3-2 Appearance of temporary cavities in gelatin blocks due to (A) full metal jacketed rifle bullet, (B) hunting rifle bullet, and (C) shotgun pellet.

M/L Importance of Wound Ballistics

Recognition of Entry & Exit wounds
Distance of Fire.
Direction of fire & Wound track.
Relative position of weapon/victim & angle of fire.
Cause of death.
Manner of death.
Identification of firearm.

Components of a Shot responsible for damage

Shot charge (bullet/pallet)
Flame & heat
Hot explosive gases
Smoke
Wad
Unburnt gun powder - tatoing
Grease from the barrel

Firearm-wound complex has four parts:

An entry wound
A track with its direction
Place of resting of bullet or shot-charge.
Exit wound

ENTRY WOUND

SINGLE HOLE:
- SIZE : depends upon skin elasticity, tail wag, explosive blast effect of gases so either proportionate to the diameter of the bullet, SMALLER or much larger having STELLATE SHAPE.
- SHAPE: depending upon the angle of firearm with the target. Circular, Oval, Elliptical, An elongated furrow.
- Inverted margins. May be everted.
- Collar of abrasion: shape depends upon the angle of firearm with the target.

FLAME

BURNING

SMOKE

Carbon particles scattered on HISTOLOGICAL examination

Carbon particles scattered on HISTOLOGICAL examination

Burning: Few inches in case of revolver & one foot in case of a Shotgun

Blackening: Absent after one yard

Burning: Few inches in case of revolver & one foot in case of a Shotgun
Blackening: Absent after one yard

Tattooing (due to unburnt gunpowder particles)

They pierce under the superficial skin layers causing “punctate abrasions of smaller blood vessels under the “skin

Beyond 2 yards, tattooing is not present
by Naseeb R. Awan

Un-burnt gunpowder particles pierce the skin while blood stains are washable

Tattooing
Blood stains

Skin changes

Bruising (at or around entry wound due to general tissue trauma) MUZZLE IMPRINT, Gases of the blast ballooning & bruising the skin/Vital reaction / Inflammatory reaction
Collar of Abrasion: Rub raw of the superficial skin layers while projectile enters the skin. More prominent in rifled firearms due to their rotational motion