Gunshot Wounds

Shotguns

Possess a smooth bore. Rifled barrels do exist for single projectiles (slugs). Can fire a single projectile (slug) or multiple pellets. Barrel length of shotguns range from 18 to 36 inches, with 26 and 28 inches being the most common. The term gauge describes the caliber of the weapon - refers to the number of lead balls of the given bore diameter that make up a pound. (The exception to this is the .410 which has a .410 inch diameter bore.) The most popular gauge of shotgun in the United States is the 12-gauge.

Chokes

The partial constriction of the bore of a shotgun barrel at the muzzle end to control shot patterns. Tighter choke equals smaller pattern of pellets. - Full - Modified - Improved Cylinder - Cylinder No matter what the gauge, weapons of identical choke will produce approximately the same size patterns at the same range.

4 Types of CONTACT Wounds

- 1. Hard - 2. Loose - 3. Angled - 4. Incomplete (A variation of angled)

4 Categories of Gunshot Wounds

1. Contact 2. Near contact 3. Intermediate 4. Distant

Appearance of Soot depends on:

1. Range 2. Propellant 3. Angle of the muzzle to the target 4. Barrel length 5. Caliber of the weapon 6. Type of weapon 7. Target material and the state of the target (bloody or non-bloody)

Handguns

1. Single shot pistols 2. Derringers 3. Revolvers 4. Auto-loading pistols (automatics)

Automatic

A firearm designed to feed cartridges, fire them, eject their empty cases and repeat this cycle as long as the trigger is depressed and cartridges remain in the feed system. Examples: machine guns, submachine guns, selective-fire rifles, including true assault rifles. This term is also commonly used for Semi-Automatic Pistols and Rifles in lea of the term

Semi-Automatic

A firearm in which each pull of the trigger results in a complete firing cycle, from discharge through reloading. It is necessary that the trigger be released and pulled for each cycle. These firearms are also called "autoloaders" or "self-loaders." The discharge and chambering of a round is either blowback operated, recoil operated, or gas operated. Note: An automatic action firearm loads, discharges, and reloads as long as ammunition is available and the trigger is depressed. A semi-automatic firearm only discharges one cartridge with each squeeze of the trigger. Often semi-automatics are referred to as "automatic".

Derringers

A variant of a single shot pistol; small pocket firearms having multiple barrels; each barrel can be fired separately

Exit Wounds

All have the same general characteristics (whether contact, intermediate or distant); Typically larger and more irregular than entrance wounds and, with rare exception, do not exhibit abrasion rings.

Auto Loading Semi-Automatic Pistols

Auto-loader in which the trigger must be pulled for every shot fired; Uses the forces generated by the fired cartridge to operate the mechanism that extracts and ejects the empty cases, loads the fresh cartridge, and returns the mechanism into position to fire the next round; Cartridges are stored in a removable magazine (clip - a device designed to facilitate the loading of a number of cartridges into a magazine)

Stippling

Forensic textbooks generally state that powder tattooing for handguns will extend to a maximum distance of 18 to 24 inches.

Near Contact wounds

Gray zone between contact and intermediate range wounds. Muzzle of the weapon is not in contact with the skin - held a short distance away. Entrance wound is surrounded by a wide zone of soot overlying seared, blackened skin. Soot is baked into the skin and cannot be completely wiped away - unburned powder may be present.

Calibers

In the US we measure calibers by hundreds or thousands of an inch. In other places like Europe it is measured in millimeters.

Revolvers

Most common type of handgun in the United States according to Dr. DiMaio in 1998 (not necessarily true today); have a revolving cylinder that contains several chambers - each chamber holds a single cartridge; Three types of revolvers: 1. Swingout 2. Breaktop 3. Solid-frame

Intermediate Range Wounds

Muzzle of the weapon is held away from the body - yet sufficiently close enough so that powder grains expelled from the muzzle along with the bullet produce "powder tattooing" of the skin; For handguns, powder tattooing begins at a muzzle-to-target distance of about 10 mm (0.394 inches)

Shored Exit Wounds

Observed in unusual conditions; Characterized by a broad, irregular band of abraded skin around the wound; In these situations, the wound is reinforced by a firm surface at the instant the bullet exits.

Single-shot Pistol

One firing chamber intergral with the barrel and must be loaded manually each time the weapon is fired

Gunshot Wounds are either:

Penetrating: Bullet enters an object and does not exit. Perforating: Bullet passes completely through an object.

Soot Deposition

Soot (carbon) produced by the combustion of the gunpowder can contain vaporized metals from the primer, bullet and cartridge case.

Keyhole Defect

The mechanism of injury used to explain keyhole lesions is that as the bullet enters the skull tangentially, the bullet is split, one portion entering the cranial cavity while the other is expelled producing the exit defect. This is not always the case as a keyhole defect may be produced by a bullet that remains virtually intact. Keyhole defects are not exclusive to entrance sites and have also been observed in exit sites

Distant Range

The only marks on the skin are those produced by the mechanical action of the bullet passing through the skin. No soot or powder tattooing is present. Range determination cannot be made for distant gunshot wounds.