Podcast
Questions and Answers
What effect does the specific gravity of tissue have on the damage caused by a bullet?
What effect does the specific gravity of tissue have on the damage caused by a bullet?
Which statement best describes the wounds caused by contact-range gunfire?
Which statement best describes the wounds caused by contact-range gunfire?
How does the design of a bullet influence the severity of injuries sustained?
How does the design of a bullet influence the severity of injuries sustained?
What typically happens to exit wounds compared to entrance wounds?
What typically happens to exit wounds compared to entrance wounds?
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What important factor must be considered to estimate the distance of a gunshot wound accurately?
What important factor must be considered to estimate the distance of a gunshot wound accurately?
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What defines the caliber of a rifled weapon's barrel?
What defines the caliber of a rifled weapon's barrel?
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Which type of firearm utilizes spiral grooves in its barrel?
Which type of firearm utilizes spiral grooves in its barrel?
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What is primarily responsible for igniting the propellant powder in a cartridge?
What is primarily responsible for igniting the propellant powder in a cartridge?
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Which of the following is NOT a characteristic of firearm wounds?
Which of the following is NOT a characteristic of firearm wounds?
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What type of powder is classified as modern gunpowder?
What type of powder is classified as modern gunpowder?
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Which of the following best describes the term 'cavitations' in the context of firearm injuries?
Which of the following best describes the term 'cavitations' in the context of firearm injuries?
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In rifled weapons, what is the role of the lands in the barrel?
In rifled weapons, what is the role of the lands in the barrel?
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What substance is primarily contained in the primer of a cartridge?
What substance is primarily contained in the primer of a cartridge?
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What is the primary effect of the gas produced by gunfire on the skin?
What is the primary effect of the gas produced by gunfire on the skin?
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What happens to the diameter of the inlet wound compared to the bullet's diameter after the bullet leaves the skin?
What happens to the diameter of the inlet wound compared to the bullet's diameter after the bullet leaves the skin?
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Which phenomenon is described by the presence of unburned particles or powder residue in the skin?
Which phenomenon is described by the presence of unburned particles or powder residue in the skin?
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What kind of marks are associated with the muzzle effect of gunfire?
What kind of marks are associated with the muzzle effect of gunfire?
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What type of tissue damage occurs due to cavitation from a bullet?
What type of tissue damage occurs due to cavitation from a bullet?
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How do metallic fragments from gunfire specifically affect the skin?
How do metallic fragments from gunfire specifically affect the skin?
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What substance in gunfire gases contributes to a pink coloration in tissues?
What substance in gunfire gases contributes to a pink coloration in tissues?
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What effect does the lubricant from the firearm have on the wound created by a gunshot?
What effect does the lubricant from the firearm have on the wound created by a gunshot?
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What is a characteristic of the exit of a bullet compared to its inlet?
What is a characteristic of the exit of a bullet compared to its inlet?
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Which of the following describes a bullet's inlet when fired at an angle?
Which of the following describes a bullet's inlet when fired at an angle?
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Which term describes the difference in size between an entrance and exit wound in bones?
Which term describes the difference in size between an entrance and exit wound in bones?
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What type of wound is formed by a bullet grazing the skin and subcutaneous tissue?
What type of wound is formed by a bullet grazing the skin and subcutaneous tissue?
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What is typically absent in the exit wound of a bullet?
What is typically absent in the exit wound of a bullet?
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What deformity can occur in a bullet fired that strikes a firm object before entering the body?
What deformity can occur in a bullet fired that strikes a firm object before entering the body?
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What distinguishes the sizes of inlet and exit wounds in bones?
What distinguishes the sizes of inlet and exit wounds in bones?
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What is the shape of inlet wounds made by bullets fired at a distance?
What is the shape of inlet wounds made by bullets fired at a distance?
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What characteristic wound shape is typically associated with new shotgun ammunition devices?
What characteristic wound shape is typically associated with new shotgun ammunition devices?
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At what distance do felt and cardboard wads typically cause a circular bruise on the skin?
At what distance do felt and cardboard wads typically cause a circular bruise on the skin?
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What primarily modifies the spread of pellets from a shotgun?
What primarily modifies the spread of pellets from a shotgun?
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Which factor is least likely to contribute to complications and sequelae from firearm injuries in the head?
Which factor is least likely to contribute to complications and sequelae from firearm injuries in the head?
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Which question is not typically part of the investigation for firearm injuries?
Which question is not typically part of the investigation for firearm injuries?
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When do exit wounds become more common in non-rifled weapons?
When do exit wounds become more common in non-rifled weapons?
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What is a possible cause of death associated with firearm injuries in the abdomen?
What is a possible cause of death associated with firearm injuries in the abdomen?
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Firearm residue on a victim can present visibly as which of the following?
Firearm residue on a victim can present visibly as which of the following?
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What occurs when a bullet breaks up during its course?
What occurs when a bullet breaks up during its course?
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Which of the following describes the initial mechanism when a sporting gun is fired?
Which of the following describes the initial mechanism when a sporting gun is fired?
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What feature characterizes contact wounds caused by non-rifled weapons?
What feature characterizes contact wounds caused by non-rifled weapons?
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At distances of 2 to 4 meters, what change occurs in the entrance wound of a non-rifled weapon?
At distances of 2 to 4 meters, what change occurs in the entrance wound of a non-rifled weapon?
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How do the effects of gunfire from non-rifled weapons compare to those from rifled weapons?
How do the effects of gunfire from non-rifled weapons compare to those from rifled weapons?
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What is the expected appearance of an entrance wound from a weapon held at right angles to the skin?
What is the expected appearance of an entrance wound from a weapon held at right angles to the skin?
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What is the result of wad injuries caused by non-metallic contents in shotgun cartridges?
What is the result of wad injuries caused by non-metallic contents in shotgun cartridges?
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What is a characteristic of wounds caused by shotgun pellets at distances greater than 4 meters?
What is a characteristic of wounds caused by shotgun pellets at distances greater than 4 meters?
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Study Notes
Firearm Injuries
- Firearms are weapons that propel a projectile using expanding gases created by the combustion of an explosive substance.
- Rifled weapons have spiral grooves with lands in the barrel. Lands bite the bullet during passage, creating a spinning motion.
- Caliber is the bore diameter of a rifled weapon's barrel and is measured as the distance between two opposite lands, typically in hundredths of an inch or millimeters.
- Rifled weapons come in long-barrel (service rifles) and short-barrel (handguns like revolvers and pistols) varieties.
- Non-rifled weapons, like shotguns, have smooth bores and fire multiple projectiles (pellets), and also wads.
- The mechanism of firing rifled weapons involves the firing pin impacting a primer (containing mercury fulminate), igniting the propellant powder, creating high pressure, and propelling the bullet from the gun.
- Firearm wounds exhibit Cavitations,(loss of substance) of the surrounding tissues due to damage, and an inlet wound and an exit wound also present a track between them both.
- Powder marks and gunshot residue may be present externally of the wound, especially at the inlet.
- Bevelling of bones is observed as a characteristic due to bullet impacting.
- The range of firing impacts tissue damage, with varying characteristics based on whether contact, intermediate, or distant.
- Contact wounds have soot, and more lacerations, and potentially a muzzle imprint.
- Intermediate-range wounds have a wider powder stippling zone.
- Distant-range wounds have a hole roughly the caliber of the projectile, with less powder stippling.
- Exit wounds are larger than entrance wounds and frequently lack gunshot residue.
- Bullet trajectory/path may change during the passage of a bone or firm tissue; an exit wound may not be directly opposite an entrance wound.
Mechanism of Firing Rifled Weapons
- Firing: The firing pin impacts the primer, igniting the explosive.
- Flash: The flash ignites the propellant powder.
- Gas Production: Burning powder generates gas pressure.
- Bullet Propulsion: High pressure propels the bullet through the barrel.
Gunpowder
- Black powder: Composed of carbon, sulphur, and potassium nitrate.
- Smokeless powder: Modern gun powder, consisting of nitrocellulose and/or nitroglycerine. Often single-base or double-base.
- Primer: Lead azide, lead styphnate, mercury fulminate, lead thiocyanate, antimony sulfide. Materials used in propellants.
Effects of Gunfire on Skin and Clothing
- Gases: Evert the wound edges, creating a cruciate.
- Flame/Burning: Produces burning effects on affected surfaces
- Smoke: Cause blackening on surfaces.
- Unburned particles (powder residue): Creates a tattooing/stippling effect on skin/cloth.
- Metallic fragments: Can become embedded in skin(gunshot residue)
Bullet Tissue Damage Mechanisms
- Laceration/Crushing: Direct mechanical damage caused by the bullet.
- Cavitations: Permanent cavity from bullet path; temporary cavity from continued acceleration of air/tissue.
- Shock waves: Compress tissue and travel ahead of the bullet.
Factors Affecting Injuries
- Bullet velocity and mass: Greater velocity/mass often leads to greater damage.
- Bullet design: Properties of the bullet (shape, construction) influences damage.
- Target distance from the muzzle: Shorter range usually results in greater damage.
- Tissue type: Density and elasticity, affect damage potential
- Bullet tumbling: Can alter the nature of damage and extent.
Range of Firing in Rifled Weapons
- Contact: immediate, wound characterized by soot, and muzzle imprint.
- Intermediate: wider powder stippling zone.
- Distant: lack of stippling, just a hole, and spread of gunshot residue less prominent.
Range of Firing in Non-Rifled Weapons
- Contact: Single, circular wound, slight soiling/burning.
- Intermediate/Distant: Wads and pellets spread, with no central injury.
Wad Wounds
- Caused by non-metallic parts (felt/cardboard wads/plastic) of shotgun cartridges.
- Vary in severity, ranging from minor bruises to fatal injuries.
- Different types of fragments travel varied distances.
Special Forms of Firearm Wounds
- Inlet wounds: Often shaped due to bullet tumbling.
- Ricochet: Bullet strikes hard surface prior to body, leading to powder marks on the intermediate surface.
- Multiple exits: Jacket separated during travel; multiple holes present.
Investigation for Firearm Injuries
- Case assessment: Determining if firearm was used.
- Wound type: In or out wound identification, as this plays a fundamental role in the investigation
- Weapon type: Identifying rifled or non-rifled weapons.
- Firing range: Estimating the distance of shot.
- Injury circumstances: Determining factors during the incident.
- Cause of death: Relationship of injury to death confirmation
- Causative weapon identification: Determining the weapon itself.
Complications of Firearm Injuries
- Death (instantaneous, delayed): Dependent on site, organs/vessels impacted.
- Neurological damage: Spinal cord issues, brain damage.
- Circulatory failure: Internal bleeding (hemorrhage), leading to shock/death.
- Internal organs damage
- Fat embolism (associated with long bone fractures)
- Pulmonary embolism (associated with long immobilization.
Firearm Residue
- Visible (blackening, grease, tattooing) and invisible (primer/powder components).
- Found on skin/clothing of shooter; victim; and at crime scene.
- Lead, Barium, antimony; present in most modern powder compositions.
X-Rays in Firearm Injury Investigation
- Used to identify bullet, pellets, fragments, or track, and to assess the site and extent/direction of impact.
- Assists in determining wound presence/location, bone/tissue defects, and the absence of a missile.
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Description
This quiz explores the mechanics and types of firearms, focusing on rifled and non-rifled weapons. It covers key concepts such as caliber, bullet dynamics, and the physiological effects of firearm injuries. Test your knowledge on these critical topics related to firearms and their impact on human tissue.
