By: Nour Abu Al Sha’ar Firearm Injuries

Some terminology Barrel: the metal tube through which the bullet is fired. Bore: the inside of the barrel, either:  Smooth bore: Shotguns.  Not smooth bore: rifles, pistols.

Muzzle: the end of the barrel out of which the bullet comes out. Primer: volatile substance that ignites when struck to detonate the powder in a cartridge.

The holder presses the firing pin which in turn strikes the primer which ignites the powder and produces large amount of hot gas. Produces very high pressure that fires the bullet forcefully through the barrel leaving the muzzle, and onto the target. What happens?

Mechanism of injury: As the missile traverses the body it causes injury by: 1.Basic contact of bullet and it’s fragments (if present) with the tissue, so larger bullets create bigger damage at the same velocity. 2.Transferring some of its available kinetic energy to the tissue around it, so increasing velocity greatly increases damage. 3.It also causes cavitations in the tissue it passes as it accelerates molecules → makes them move centrifugally away from the axis of the bullet.  Bullets do not typically follow a straight line to the target. Rotational forces are in effect that keep the bullet off a straight axis of flight.

Mode of injury depends on the velocity of the missile -Slow velocity (<340 m/s) speed of sound in air or less -High velocity (1500 m/s) faster! High velocity missile causes a shockwave around it’s track → severe disruption → ↑ tissue pressure and more damage. So a 10mm wide bullet may cause a 15mm wide track of damage… SO…

ShortLong Types of firearm weapons

Non-rifled: only long Rifled: short and long

Smooth bore weapon (Shotgun): A gun with a smoothbore that shoots cartridges that contain "shot" or small metal pellets (of lead or steel) as the projectiles. Ammunition: A shotgun shell(cartridge) may contain one large projectile (called a slug), a few pellets of large shot, or many tiny pellets. Cartridge made of a cylinder fitted into a metal base contains charge of propellant, wads, and shots. Range is the most important factor, and can be estimated in over half of cases… Close range wounds are severe, but at even relatively short distances, wounding may be minimal.

Non-rifled weapons Types of missiles

Look for any wads in the tissues before closing the wound to prevent possible infection…so not just the bullets/pellets.

The rifle weapon: Rifles differ from shotguns in the length of the barrel and the presence of a butt stock. They fire one projectile at a time through a thicker barrel that has spiral grooves on its inner surface → rotational movement. They are much more accurate and shoot more powerful cartridges than handguns. Ammunition: metal cylinder loaded with explosive propellant and bullet.

Rifle bullet/pistol bullet

Extras Solid organs such as the brain and the liver are affected more than the spongy lung. In most of the shooting cases seen by forensic pathologist death will have occurred rapidly, however when it is delayed secondary damage from infarction, local necrosis of muscles and organs, and infections must always be kept in mind. Modern propellants consist of nitrocellulose which is characteristically colored and found in the vicinity of the wounds.

Characters of firearm injuries 1- Loss of substance 2- Presence of inlet and/or exit 3- Powder marks 4- Beveling of flat bones

Suicide and Homicide: Suicide: must show wounds whose range is within the arm's reach the weapon must be present. Suicides shoot themselves in sites of election which compromise the mouth, the front of the neck, the forehead, the temples and the front of the chest. Homicide: Multiple firearm wounds suggest homicide. Inaccessible part of the body. Wounds outside the range of arms reach. People almost never shoot themselves in the eyes or at the back, and women rarely commit suicide with guns; so a shot woman is a murdered woman until proven other wise.