Ballistics

Ballistics

The scientific study of projectiles and firearms, focusing on the movement, behavior, and effects of bullets, cartridges, and guns.

Firearm

A weapon capable of firing a projectile using gunpowder or another explosive charge. Types include handguns, rifles, shotguns, and machine guns.

Caliber

The internal diameter of a gun barrel, typically measured in inches or millimeters.

Rifling

The spiral grooves cut into the barrel of a firearm to make a bullet spin for accuracy, leaving a unique pattern on the bullet.

Lands and Grooves

Lands are the raised portions of the rifling inside the barrel; grooves are the indented portions that cause the bullet to spin.

Cartridge (Round)

The complete ammunition unit, consisting of the bullet, casing, gunpowder, and primer.

Bullet

The projectile expelled from a firearm when it is fired, made of materials like lead or copper.

Firing Pin Impression

A mark left on the primer of a cartridge case when the firing pin strikes it, unique to each firearm.

Breechface Marks

Patterns left on the cartridge case by the back of the firearm when fired, used in firearm identification.

Extractor and Ejector Marks

Extractor marks are scratches made by the extractor when removing a spent cartridge; ejector marks are left when the ejector expels it.

Gunshot Residue (GSR)

Tiny particles of unburned gunpowder and metal that are expelled when a firearm is discharged.

Trajectory

The path a bullet follows after being fired, influenced by gravity, wind resistance, and obstacles.

Stippling (Tattooing)

Small burns or abrasions on skin caused by unburned gunpowder when a gun is fired at close range.

Ballistic Fingerprinting

The process of analyzing markings on bullets and cartridge cases to identify the firearm that fired them.

Serial Number Restoration

A forensic technique to recover filed-off or damaged serial numbers on firearms.

Bullet Wounds

Entrance wounds are smaller and cleaner, whereas exit wounds are larger and more irregular.

Hollow-Point Bullet

A bullet designed to expand upon impact, creating more damage.

Full Metal Jacket (FMJ) Bullet

A bullet encased in a harder metal shell to prevent expansion, often used in military applications.

Shotgun Shell

A type of ammunition used in shotguns, containing multiple small pellets or a single slug.

Ballistics Database

The NIBIN is a computerized system that stores and compares ballistic evidence from firearms and crime scenes.

Components of a Bullet

A bullet consists of a core, and may have a jacket for increased penetration.

Bullet Composition

Bullets are made from materials like lead, copper, or steel, affecting their behavior upon impact.

Types of Bullets

Includes Full Metal Jacket, Hollow Point, Soft Point, Frangible, and Armor-Piercing bullets.

Internal Ballistics

The study of a bullet's movement through the barrel and the explosive forces that propel it.

External Ballistics

The study of a bullet's flight, influenced by gravity, wind resistance, and bullet shape.

Terminal Ballistics

The study of how a bullet interacts with a target after firing.

Rifling Marks

Unique scratches on a bullet formed by the grooves in the barrel, aiding in firearm identification.

Striations

Microscopic scratches on a bullet caused by imperfections in the gun barrel.

Bullet Trajectory Analysis

Investigators analyze bullet paths to reconstruct crime scenes.

Entrance vs. Exit Wounds

Entrance wounds are smaller and rounder; exit wounds are larger and irregular.

Close-Range vs. Long-Range Wounds

Close-range wounds show stippling; long-range wounds lack stippling.

Ricochet and Deflection

Bullets may bounce off surfaces before hitting a target, changing their trajectory.

Ballistic Databases

Systems like NIBIN store bullet and cartridge case markings for law enforcement use.

Test-Firing and Comparison

Forensic experts fire firearms into ballistic gel to compare with crime scene evidence.

Bullet Fragmentation

Some bullets break apart upon impact, complicating recovery.

Deformation

Bullets may change shape upon impact, affecting forensic matching.

Environmental Effects

Factors like water, heat, and conditions may alter a bullet's condition over time.

Definition of a Firearm

A firearm uses controlled explosions to launch a projectile at high speed.

Categories of Firearms

Firearms include handguns, rifles, and shotguns, with each having distinct features.

Handguns

Short-barreled firearms designed for one-handed use; include revolvers and semi-automatic pistols.

Rifles

Long-barreled firearms with rifling designed for two-handed use, often used for hunting.

Shotguns

Firearms that shoot multiple pellets or a single slug, typically for close-range use.

Special Firearm Categories

Includes submachine guns, personal defense weapons, machine guns, and assault rifles.

Firearm Action Types

Types include single-shot, bolt-action, lever-action, pump-action, semi-automatic, and fully automatic.

Firearms in Forensic Investigations

Techniques for matching guns to bullets and analyzing scene evidence.

Definition of a Pistol

A semi-automatic handgun designed for one-handed use.

Major Components of a Pistol

Includes frame, slide assembly, and action/trigger mechanism.

Frame

The foundation of the pistol housing components.

Slide Assembly

The upper moving part of the pistol that cycles during firing.

Ejection Port

The opening on the slide where spent shell casings are ejected.

Action Mechanism

Controls firing, loading, and safety in a firearm.

Safety Features of a Pistol

Includes manual safety, trigger safety, grip safety, and drop safety.

Pistol Operation Cycle (Firing Sequence)

The sequence of events from loading a round to ejection.

Common Types of Pistols

Includes hammer-fired like single-action and double-action, and striker-fired models.

Introduction to Cartridge Anatomy

A cartridge consists of several components working together for firearm operation.

Components of a Cartridge

Includes bullet, case, primer, and propellant.

Types of Cartridges

Includes centerfire, rimfire, and shotshell cartridges.

Understanding Cartridge Caliber

Refers to the diameter of the barrel and bullet size.

Ammunition Loading and Fire Cycle

Describes the process from loading to firing and ejection.

Cartridge Identification

Based on headstamps which provide information about the manufacturer.

Firearm Markings and Toolmarks

Unique characteristics left on bullets and cases during firing.

Restoring Serial Numbers

Techniques used to recover obliterated serial numbers on firearms.

Comparison of Fired Ammunition

Analyzing fired cases and bullets to match them to specific firearms.

Firearm-Specific Bullet Markings

Unique impressions left by specific firearms during firing.

Importance in Forensic Ballistics

Helps identify firearms and link crime scenes.

Legal Implications and Use in Court

Bullet markings used as forensic evidence in trials.

Introduction to Gunshot Residue (GSR)

Microscopic particles expelled when a firearm is discharged.

Methods of Collecting GSR

Includes swabbing, tape lifting, air sampling, and sampling from objects.

Techniques for Analyzing GSR

Includes methods like scanning electron microscopy and inductively coupled plasma mass spectrometry.

Importance of GSR in Forensic Investigations

GSR can confirm or exclude a suspect's involvement in firearm discharge.

Challenges and Limitations of GSR Testing

Includes issues like environmental contamination and transfer of residues.

Introduction to Bullet Trajectory

The path a bullet follows after being fired influenced by various factors.

Key Factors Influencing Bullet Trajectory

Includes initial velocity, gravity, air resistance, bullet spin, and wind.

Calculating Bullet Trajectory

Factors such as muzzle velocity and angle of elevation affect trajectory calculations.

Bullet Trajectory in Practical Use

Factors critical for sniping, military applications, and hunting.

Fastest Weapon in the World

The mechanical Gatling gun known for its rapid fire.

Bullet Identification in Forensics

Investigators use striation comparisons to link bullets to firearms.

Bullet Trajectory Reconstruction

Investigators trace bullet paths to determine shooter position.

Hard Armor

Stops high-velocity rifle rounds, typically made of ceramic or steel.

Soft Armor

Can stop handgun rounds, usually made of materials like Kevlar.

Temporary Cavity

Created by the bullet's energy momentarily pushing surrounding tissue outward.

Crushing Injury (Permanent Cavity)

Determines permanent damage caused directly by a bullet's path.

Bullet Speed and Energy Relationship

Higher bullet speed results in increased energy transfer.

Best Bullet Type for Law Enforcement

Hollow points are preferred for effective stopping power.

Police Shootings and Engagement Distance

Average shootings occur at distances of 10 feet or less.

Development of Ballistics

Firearms have evolved significantly over the past 300 years.

Early Bullet Problems

Musket balls had reliability issues due to poor accuracy and design.

Ballistics Overview

The study of the motion and impact of projectiles, particularly bullets.