Glossary

action the working mechanism for chambering, cocking, firing, and ejecting in a firearm. Examples include falling block, rolling block, lever, and slide.

AFIS (automated fingerprint identification system) a system that electronically compares questioned fingerprints against a database of fingerprints composed mainly of persons who have served in the military or who have been arrested ALS (alternate light source) a source of light that emits only a certain wavelength of light such that certain components of latent fingerprints will fluorence and be made visible; forensic science light amido black organic compound that reacts with blood to produce a blue-black color angle of impact the interior (acute) angle of the axis of the path of a bullet connecting with a target annular rim in firearms examination, the outer circumference of the cartridge case base (location of primer in rim fire cartridges) antimony sulfide a component of most primers that acts as a fuel ballistics the study of projectile motion, often confused with firearms identification barium nitrate a component of most priming mixtures that acts as an oxidizer bird shot a general term for any shot smaller than buckshot bolt action a firearm design in which the breech is always in line with the bore and the weapon is loaded, unloaded, and cocked manually. There are two principal types of bolt action firearms: rotating and straight pull.

bore the interior of a barrel forward of the chamber breech block a metal block that closes the aperture at the back part of a rifle or gun barrel breech face the part of the breech block or bolt that is against the base of the cartridge case or shot shell during firing broach in firearms manufacture, a rifling cutter that cuts all the grooves simultaneously buckshot lead pellets ranging in diameter from 0.20 inch to 0.36 inch and normally fired in shotguns bullet the projectile portion of a cartridge bullet jacket a metallic covering over a bullet core that allows the bullet to feed smoothly through the bore of an automatic or semiautomatic firearm caliber the cross-sectional diameter of the barrel of a firearm, measured from land to land calipers a device consisting of two movable jaws or legs used to measure distance, thickness, or width carbon powder fingerprint powder made from finely divided carbon cartridge an individual unit of ammunition consisting of a cartridge case, bullet, powder charge (propellant), and primer cartridge case the container encasing the individual components of a round of ammunition center fire a cartridge design in which the primer is located at the center of the base (head) chamber in a firearm, the rear part of the barrel bore that has been machined for a specific cartridge. Revolver cylinders are multicham-bered.

chamber marks individual characteristics imparted to the chamber walls during machining chemical enchancement in fingerprinting, the use of any variety of chemical reagents to assist in the visualization of a latent fingerprint through chemical reaction with one of the components of the fingerprint residue chemical etchant a chemical reagent used to dissolve metals and assist in the restoration of obliterated serial numbers choke in a shotgun, constriction in the muzzle end of the barrel to reduce scattering of the shot class characteristics qualities that distinguish a collection of items as members of a discrete group, particularly those caused by the processes that made them clip See MAGAZINE

cock to place a firing mechanism under spring tension dactylography the study of fingerprints for the purposes of identification disk powder a form of gunpowder that is extruded (forced through a mold) and cut into small disks double action a type of firing system in which a single pull of the trigger cocks and releases the hammer ejection the expulsion of a fired cartridge case or shot shell ejector marks the marks left on the base (head) of a cartridge case or shot shell by the ejector during the process of ejection etch to produce a mark on a hand material such as metal by corroding away part of the surface fingerprint card a paper card divided into sections, one for each finger and one for each palm surface, for collecting ink imprints of a person's fingerprints fingerprint residue a combination of water, salt, protein compounds, and oils firearm a small arms weapon, such as a rifle or pistol, from which a projectile is fired by gunpowder firing pin a plunger in the firing mechanism of a firearm that strikes the cartridge primer and initiates ignition firing pin impression the impression that a firing pin makes at the base of the cartridge upon impact with the primer friction ridge the raised areas of the palm surface of the hand and the sole surface of the foot that allows gripping. Friction ridges are the patterns recorded in fingerprinting. function testing the examination of a firearm for operability and firing capability general rifling characteristics the number, width, and direction of twist of rifling grooves Griess test a chemical test for nitrites, used to detect gunpowder residue around bullet holes grooves in firearms, the helical groove in the interior of a barrel to impart spin on the bullet; rifling gunshot residue gunpowder and primer residue that a firearm discharges when it is fired hammer the part of a firearm that by its fall or action causes a firing pin to strike the primer, causing the ignition of the primer hammer forging the process of forming the interior and exterior of a firearm barrel by hammering identification the determination that two objects, one a known and the other an unknown, had a common origin based on the presence of individual characteristics individual characteristics accidental, random marks used to identify tool marks as coming from a particular weapon or tool. inkless fingerprinting a special fingerprint process that puts a clear substance on the fingers and then transfers the ridge detail to a special paper, producing a visual fingerprint without the use of fingerprint ink iris the colored area of the eye that surrounds the lens land in firearms, the raised area between two grooves in the interior of a barrel to impart spin on the bullet; rifling latent fingerprint a fingerprint that is not visible to the unaided eye lead azide a chemical compound used in most primers to aid in the ignition process leuco crystal violet an organic chemical that reacts with blood to produce a violet color; used as a presumptive test for the presence of blood lever action a type of firearms action that uses a lever to move the breech mechanism luminol an organic compound that reacts with heme (tiny particples in blood) to produce a blue glow in the absence of light, which visualizes the presence of unseen blood in a crime scene magazine a device that holds and automatically loads cartridges into the chamber of a firearm magna powder finely divided iron filings used to enhance latent fingerprints on paper surfaces major case prints inked fingerprints that include all fingers and the palms of both hands micrometer a precision measuring device used to measure small distances or thicknesses negative impression the result of touching a surface with a clean hand or finger and removing surface material; an indentation or disturbance of the surface

NIBIN (National Integrated Bullet Identification Network) a system for electronic comparison of bullets and cartridge cases entered into databases across the country ninhydrin an organic compound that reacts with amino acids to produce a purple-colored complex nitrocellulose powder a smokeless propellant whose principal ingredient is nitrocellulose, a low explosive nitroglycerin a high explosive and component of double-based gunpowder patent fingerprint a fingerprint that is visible to the unaided eye pellet a common term for the small, spherical shot used in shot shells plastic fingerprint a fingerprint impressed into a pliable medium, such as putty plumb bob a cone-shaped metal object used to establish a line perpendicular to the earth; the plumb bob is attached to a loose wire or line and suspended with the point of the bob oriented toward the ground polygonal rifling rifling with rounded edges instead of the usual square edges positive impression the result of a transfer of material, such as blood, from the finger onto another surface powder stippling the speckled pattern made by powder particles striking the skin and embedding and/or leaving a burn or bruise primer in firearms, a shock-sensitive explosive mixture that initiates burning of the propellant propellant the powder charge inside a shot shell or cartridge case that provides thrust to the projectile retina the area of the eye behind the cornea, lens, pupil, and iris that contains the optic nerve rifling See grooves rifling characteristics See general rifling characteristics slug a single projectile for a shotgun sodium rhodizonate a chemical test used to determine if lead residues are present on a surface, such as fabric soot carbonaceous material produced by the combustion of gunpowder, resulting in fine black particles superglue fuming the process of making latent fingerprints visual through contact with fumes of cyanoacrylate ester tool mark any impression, scratch, gouge, cut, or abrasion made when a tool is brought into contact with another object tool mark, impressed the mark produced when a tool presses against another surface with enough force to leave an impression tool mark, striated a mark produced with a combination of force and motion

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