Injury by Gunfire/Gunshot Wound information

Derringers

- A variety of single shot pistol - Small pocket firearms having multiple barrels

Shotguns

- Possess a smooth bore. - Rifled barrels do exist for single projectiles (slugs). - Can fire a single projectile (slug) or multiple pellets. - May be: - Autoloaders - Over/Unders - Side by side - Bolt Action - Single Shot -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.

Four Broad Categories of Gunshot Wound

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

Five Categories of Small Arms

1. Handguns 2.Rifles 3.Shotguns 4.Submachine guns 5.Machine guns

Four types of contact wounds

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

Size, Intensity and Appearance of Soot Patterns 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)

Four Basic Types of Handguns

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

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.

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

Derringers

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

Graze Wound

A wound in which a bullet strikes the skin at a shallow angle, producing an elongated area of abrasion without actual perforation or tearing of the skin.

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 Pistols/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)

Angled-Contact Wounds

Barrel of the weapon is held at an acute angle to the skin; complete circumference of the muzzle is not in contact with the skin; Gas and soot escape producing an eccentrically arranged pattern

Contact Wounds Over Bone

Contact wounds in regions where a thin layer of skin and subcutaneous fat overlies bone will usually produce a stellate or cruciform appearance. The unusual appearance of these wounds over bone is due to the effects of gases from the discharge. When the stretching exceeds the elasticity of the skin, it will tear.

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.

Caliber

In the United States and all English-speaking countries the diameter of the bore of rifled small arms is designated in hundredths or thousandths of an inch. Thus we have rifles, pistols and revolvers of .22, .25, .30, .32, .38 and .45 caliber or .220, .257, .357, and .405 caliber. On the continent of Europe and elsewhere the calibers of such weapons are designated in millimeters, as 6.5 mm, 7 mm, 8 mm and 9 mm. i.e., 6.35 mm = .25 caliber and 9 mm = .38 caliber

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 integral with the barrel and must be loaded manually each time the weapon is fired

Gunshot wounds are either penetrating or perforating

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. Deposition 8-12 inches

Rifle

The firing of a bullet contains: soot, powder, flash.

Keyhole Defects

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.

Hard Contact Wound

The muzzle of the weapon is jammed "hard" against the skin, indenting it (skin envelopes the muzzle); Wound edges are seared by the hot gases of combustion and blackened by the soot deposition; this soot is embedded in the seared skin and cannot be completely removed by washing.

Loose-Contact Wound

The muzzle, while in complete contact with the skin, is held lightly against it; Soot carried by gas is deposited in a zone around the entrance; Soot can be easily wiped away; A few grains of unburnt gunpowder may also escape and be deposited in this zone

Distant Range Gunshot Wounds

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.

Contact Wounds

The weapon is held against the surface of the body at the time of discharge.

Revolvers

Until the 1970's, most common type of handgun in the United States. 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 (DiMaio, 1998)

Incomplete-Contact Wounds

Variation of angled-contact wounds; Muzzle of the weapon is held against the skin, but because the body surface is not flat, there is a gap between the muzzle and the skin; A jet of soot-laden gas escapes producing an area of seared, blackened skin; Most often seen in self-inflicted wounds to the head due to long arms

Powder Tattooing (Stippling)

•Numerous reddish-brown to orange-red punctate lesions surrounding the wound entrance •An antemortem phenomenon indicating the individual was alive •Are not powder burns, rather punctate abrasions •Powder tattooing cannot be wiped off •Powder tattooing of the palms of the hands and the soles of the feet is very rare •Stippling may be due to powder or other materials such as shotgun filler, intermediary target, etc. •Powder tattooing is just one form of stippling with the term referring unquestionably and exclusively due to deposition of powder grains

Choke

•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