Firearms, Tool Marks, and Other Impressions

This set of flashcards covers key vocabulary terms from Chapter 9 on Firearms, Tool Marks, and Other Impressions, aiding in the study of forensic science and its terminology.

bore

The interior of a firearm barrel.

breechface

The rear part of a firearm barrel.

caliber

The diameter of the bore of a rifled firearm.

choke

An interior constriction placed at or near the muzzle end of a shotgun’s barrel.

distance determination

The process of determining the distance between the firearm and a target, usually based on the distribution of powder patterns or the spread of a shot pattern.

ejector

The mechanism in a firearm that throws the fired cartridge case from the firearm.

extractor

The mechanism in a firearm by which a cartridge of a fired case is withdrawn from the chamber.

firearms identification

A discipline mainly concerned with determining whether a bullet or cartridge was fired by a particular weapon; not to be confused with ballistics.

gauge

The diameter of the shotgun barrel. Originally, the number of lead balls with the same diameter as the barrel that would weigh a pound.

Greiss test

A chemical test used to develop patterns of gunpowder residues around bullet holes.

grooves

The cut or low-lying portions between the lands in a rifled bore.

lands

The raised portion between the grooves in a rifled bore.

rifling

The spiral grooves formed in the bore of a firearm barrel that impart spin to the projectile when it is fired.

tool mark

Any impression, cut, gouge, or abrasion caused by a tool coming into contact with another object.

impression

An impression left by an object, such as a shoe or tire mark, in a softer surface.

individual characteristics

Unique features that can relate a bullet to a specific firearm.

class characteristics

Shared features that can categorize evidence into a specific group.

forensic significance

The importance of evidence in a legal context, often related to an investigation.

casting

The process of making a mold of an impression left at a crime scene.

lifting

The technique used to preserve impressions by transferring them onto a lifting medium.

substate control

An unstained object adjacent to an area on which biological material has been deposited.

accurate course

The intended path that a projectile follows.

NIBIN

National Integrated Ballistics Information Network, a program that stores and matches ballistic evidence.

ballistics

The study of projectiles in motion.

FBI

Federal Bureau of Investigation, the agency responsible for maintaining national databases of criminal evidence.

ATF

Bureau of Alcohol, Tobacco, Firearms and Explosives, the agency responsible for enforcing laws related to firearms.

latent fingerprints

Unseen fingerprints that can be lifted from surfaces.

swing-out revolver

A type of revolver where the cylinder swings out to the side for loading.

break-top revolver

A type of revolver that hinges at the top to load cartridges.

solid-frame revolver

A revolver without a mechanism to uncover all firing chambers at once.

semiautomatic pistol

A pistol that fires one shot per trigger pull and automatically reloads.

double-action firearm

A firearm that cocks and reloads after each shot with a single trigger pull.

single-shot firearm

A firearm that requires manual loading of each round.

ammunition

The projectiles and explosive substances used in firearms.

cartridge case

The container that holds the gunpowder and bullet in a cartridge.

muzzle-to-target distance

The distance from the firearm's muzzle to the target.

firearms evidence

Any physical evidence associated with firearms.

microscopic examination

The detailed inspection of evidence at a microscopic level.

electrophoresis

A technique for separating charged molecules based on their size.

touch DNA

DNA left on an object through direct contact.

Y-STRs

Short tandem repeats located on the Y chromosome.

probabilistic genotyping

A method for analyzing complex DNA mixtures.

alleles

Alternative forms of a gene that determine specific traits.

genotype

The genetic constitution of an organism.

phenotype

The expressed physical characteristics determined by the genotype.

DNA profiling

Analyzing distinct patterns in an individual's DNA.

DNA polymerase

An enzyme that synthesizes new DNA strands during replication.

restriction fragment length polymorphisms (RFLPs)

Differences in DNA sequences that result in varying lengths of DNA fragments.

polymerase chain reaction (PCR)

A technique to amplify DNA segments for analysis.

striation markings

Unique markings left on a bullet by a firearm's barrel.

comparison microscope

An instrument used for detailed comparison of two pieces of evidence, such as bullets.

crime scene reconstruction

The process of recreating an event to determine the sequence of actions.

polydactyl

Having more than the usual number of digits.

kinship analysis

A method of determining familial relationships using DNA.

DNA sequencing

The process of determining the precise order of nucleotides in a DNA molecule.