Chapter 16

Question 1

Action

Alternative light sources (als): Light sources that employ light of different wavelengths (colors) to
visualize the components of an impression.

Barrel: The metal pipe that guides the initial flight of the bullet.
Breech: The end of the gun barrel nearest to the action.
Breech block (or face): The back of the firing chamber.
Breech-loading Firearm: A weapon in which the ammunition and bullet are placed directly into the
firing chamber without having it put down the barrel.
Broach cutter: A tool used to simultaneously cut all of the rifling grooves by forcing the cutter head
down a smooth, drilled-out gun barrel while rotating the cutter with a characteristic twist rate.

Button Rifling: A process in which a small, shaped form is forced down the smooth gun barrel at very
high pressures, compressing rather than cutting the metal into the grooves to form a rifled barrel.

Cartridge: Ammunition made up of casing, primer, powder, wadding and bullet.
Casting: A physical replica of an impression, formed by a moldable material, that sets into an actualsized,
permanent reproduction of the original impression.
Chamber: The enclosure in a gun’s design that contains the cartridge when ready to fire.
Dental stone: A gypsum product that when mixed with water and pored into a mold sets to form a hard,
strong and stable solid that doesn’t require reinforcement.

Answer 1

The mechanical apparatus of a firearm that loads, fires and ejects the cartridge.

Question 2

Drag

Answer 2

The force that opposes the forward motion of the bullet created by air resistance.

Question 3

External (intermediate) ballistics

Answer 3

The study of the flight of the bullet from the time it leaves the end of the gun barrel until it reaches the target.

Question 4

Ballistics

Answer 4

The study of how projectiles move through space.

Question 5

Caliber

Answer 5

The diameter of the gun barrel in 1/100th of a inch.

Question 6

Air gun

Answer 6

Weapons that move a projectile solely by the release of stored gas pressure rather than through combustion.

Question 7

Fixed ammunition

Flintlock weapon: Firearms that use a spark created by moving a piece of flint over a steel plate
(“frizzen”) to ignite a small primer charge that then sets fire to the main charge.
Firearm: An assembly consisting of a barrel and a mechanical action that allows a projectile(s) to be
propelled forward through the action of an extremely fast combustion reaction.
Firearms identification: The process of determining “if a bullet, cartridge case or other ammunition
component was fired by a particular firearm.”

Answer 7

Ammunition that combines primer, an accurately measured main charge and the bullet all enclosed in a single, easily handled, water-tight casing.

Question 8

Gunshot residues

Answer 8

Deposits of unreacted explosive materials and solid combustion byproducts that are discharged from openings in the gun into the nearby environment upon firing.

Question 9

Shotgun

Answer 9

A type of long gun without rifling that uses ammunition containing either many small pellets (shot) packed into a single cartridge or a single, solid projectile (slug).

Question 10

Visible impressions

Answer 10

Impression evidence that is readily observable without any visualization aids

Question 11

Terminal Ballistics

Answer 11

The study of what happens when a projectile hits its target.

Question 12

Types of Ballistics

Answer 12

Internal, external, and terminal

Question 13

Types of Ballistics

Answer 13

Internal, external, and terminal

Question 14

Handgun

Answer 14

Smaller firearms that are designed for operation using one hand.

Question 15

Serial number restoration

Answer 15

The process of making visible serial numbers stamped into a gun that have been filed or ground away.

Question 16

Primer

Answer 16

The shock sensitive compound that ignites the main charge of a cartridge upon being struck.

Question 17

Revolver

Answer 17

A firearm in which ammunition is moved into place for firing by means of rotating a cylinder that contains a number of separate firing chambers loaded with filled cartridges.

Question 18

Positive image

Answer 18

An image created when an object leaves something behind on the surface which can be visualized.

Question 19

Rifling

Answer 19

Spiral grooves inside of the gun’s barrel which cause the projectile to spin about its long-axis.

Question 20

Round

Answer 20

An intact unit ammunition (primer, bullet or “slug” and main charge).

Question 21

Plastic impressions

Answer 21

Impression evidence that have been formed when an object is imprinted into a soft, moldable material.

Question 22

Gravity

Answer 22

The force that constantly pulls objects downward with a constant force, defined as F = mg (where m is mass and g is the gravitational constant).

Question 23

Grooves

Answer 23

The places where some of a gun’s barrel metal has been removed (rifling) or shaped to create a depression.

Question 24

Grooves

Answer 24

The places where some of a gun’s barrel metal has been removed (rifling) or shaped to create a depression.
(Makes gimps on the bullet, raised parts)

Question 25

Shotgun gauge

Answer 25

Number of pellets per 1 Ilb (12 gauge- 12 pellets that weigh one pound)

Question 26

Gunpowder

Answer 26

An explosive chemical mixture of carbon, potassium nitrate and sulfur that undergoes a rapid oxidation reaction and is used to propel projectiles in firearms.

Question 27

Gunpowder

Answer 27

An explosive chemical mixture of carbon, potassium nitrate and sulfur that undergoes a rapid oxidation reaction and is used to propel projectiles in firearms.

Question 28

Muzzle

Answer 28

The very end of the gun barrel where the bullet exits the weapon.

Question 29

Negative image

Answer 29

An image formed when some material covering a surface is material is removed by contact.

Question 30

National Integrated Ballistics Information Network (NIBIN)

Answer 30

A database used to compare stored firearm pattern information with unknown (crime scene recovered) patterns.

Question 31

Muzzle-loading firearm

Answer 31

A weapon in which the bullets and ammunition are loaded directly down the barrel of the gun.

Question 32

Kinetic energy

Answer 32

The energy of motion that is given by the expression of KE = ½ mv2 (where m is the mass and v is the velocity of the moving object).

Question 33

Internal (initial) ballistics

Answer 33

The consideration of the part of a bullet’s path that occurs within the gun itself.

Question 34

Stria (striations)

Answer 34

Tiny, random imperfection marks transferred between two objects that pass with direct contact.

Question 35

Lands

Answer 35

The portions of the inside surface of a rifled gun barrel that project farthest into the center of the barrel adjacent to grooves. (Makes limps, indented parts on bullets)

Question 36

Magnum

Answer 36

A cartridge containing more than the standard amount of powder which delivers more power to the bullet.

Question 37

Latent impression

Answer 37

Impression evidence that is not immediately observable but which can be made visible using a variety of techniques.

Question 38

Polygonal rifling

Answer 38

An alternative to the traditional lands and grooves rifling where “hills” and “valleys” form a more rounded, polygonal pattern.

Question 39

Impression evidence

Answer 39

Items of evidence that carry the lasting and observable marks from contact with another object.

Question 40

Spin (or gyroscopic) stabilization

Answer 40

The rotational movement of an elongated projectile around its long axis which greatly improves its aerodynamic properties allowing it to go much farther and with increased precision and accuracy.

Question 41

Two-dimensional impression

Answer 41

Impressions that occur when an object comes into direct contact with a hard surface or material that is not indented or molded by contact with the object but onto which patterns can be transferred by the deposition or removal of materials.

Question 42

Twist rate

Answer 42

The length of a gun barrel in which the rifling makes one full rotation (360°).

Question 43

Three-dimensional impression

Answer 43

Impressions that occur when an object comes into contact with a soft or moldable substance to leave behind an exact three-dimensional imprint of the original object.