Firearms

Question 1

Two general categories of firearms

Answer 1

Handguns

Long guns

Question 2

Handguns are generally designed to:

Answer 2

be held and fired with one hand

Question 3

Two classifications of handguns

Answer 3

single action

double action

Question 4

Single action handguns

Answer 4

requires that the hammer be manually cocked back before each shot is fired

Question 5

double action handguns

Answer 5

will automatically cock the hammer back when the trigger is pulled

will also reload the firing chamber after the current round is fired

Question 6

Three types of handguns

Answer 6

single shot handguns

revolvers

semi automatics

Question 7

Single shot handgun

Answer 7

can only fire one shot at a time

chamber needs to be manually loaded with a cartridge before each shot is taken

Question 8

Revolvers

Answer 8

multiple firing chambers

chambers located within a rotating cylinder

cylinder rotates clockwise or counter clockwise as each shot is fired

each chamber holds a single cartridge

chambers line up with the barrel when rotated

cartridge casings have to be manually removed/ejected

Three types: swing out, break top, solid frame

Question 9

Semiautomatic Handguns

Answer 9

removable magazine within the grip of the weapon

magazine is loaded with cartridges (live rounds)

load first round by pulling back the slide and causing the hammer to cock

once the slide is released the cartridge is loaded into the firing chamber

when the cartridge is fired, gases cause the casing to eject, the hammer is cocked, and the next round is loaded

one shot per trigger pull

Question 10

Long guns are either:

Answer 10

rifles

shotguns

Question 11

Long guns are designed to:

Answer 11

be fired while resting on the shoulder of the operator

there are differences in ammunition and barrel

Question 12

Rifle Ammunition

Answer 12

traditional cartridge but larger in size

Question 13

Rifle Barrel

Answer 13

has lands and grooves

Question 14

Shotgun ammunition

Answer 14

shell: contains ball shaped projectiles called “shot”

Question 15

Shotgun barrel

Answer 15

smooth
no lands or grooves

choke: narrowing of the barrel

single or double barreled

Double barrel can be horizontally or vertically situated

Can have different choke diameters

Question 16

When a barrel is hollowed out by drilling:

Answer 16

microscopic striation marks are left

Random and unique markings

No two rifled barrels have identical striation markings

Question 17

Caliber

Answer 17

diameter of the bore

Question 18

Calibers are calculated by:

Answer 18

measuring the diameter between opposite lands

Question 19

Caliber may not be an exact measurement:

Answer 19

bore diameter may fall within range

Question 20

Caliber can be recorded in two ways:

Answer 20

hundredths of an inch

millimeters

Question 21

What happens when a weapon is fired?

Answer 21

When the trigger of a gun is squeezed, a firing pin makes contact with the back end of the cartridge and ignites the explosive charge contained in the primer

The primer then ignites the propellant, or gunpowder, which is the main explosive component of a cartridge

Question 22

What path does a bullet take when fired?

Answer 22

Travels through barrel

engaged by rifling

grooves guide bullet through barrel

rapid spin results

bullet travels on a true and accurate course - steady through air, does not tumble end over end

Question 23

When attempting to link a bullet with a suspecting weapon, what should be compared?

Answer 23

the bullet and a test fired bullet from the suspected weapon

Question 24

Because shot guns have smooth barrels, projectiles that pass through have:

Answer 24

no characteristic markings

Question 25

The shot recovered at a crime scene can be weighted and measured for:

Answer 25

determination of the size of shot used in the shell

Question 26

The size and shape of the recovered wad may also help determine:

Answer 26

the gauge of the shotgun used and may indicate the manufacturer of the fired shell

Question 27

DRUGFIRE

Answer 27

Developed by the FBI in the 1990s

Emphasized cartridge case imagery but also included bullets

Used microscope and video camera for identification of individual characteristics

Question 28

IBIS

Answer 28

Integrated Ballistic Identification System

Developed by the ATF in the 1990s

Processed digital microscopic images on bullets and cartridge casings

Incorporated two software programs: Bullet proof (analyzed bullets) and brasscatcher (analyzed casings)

Question 29

NIBIN

Answer 29

National Integrated Ballistics Information network

1999

The FBI and ATF join forces

Unified system that incorporates DRUGFIRE and IBIS technologies

ATF is responsible for system sites

FBI is responsible for communications network

Question 30

Without a weapon, recognizable characteristics are used

Answer 30

What is observed around the bullet hole?

Heavy concentration of residue

Scorch marks from flame discharge of weapon

Melted fibers

Stellate patterns

Halo of vaporous lead

bullet wipe around hole

Question 31

Clothing collected at a scene may be submitted to the laboratory for presence of GSR if:

Answer 31

not readily visible due to color or patterns of clothing

Question 32

The Dos and Don’t of Firearms Collection

Answer 32

Do assume the weapon is loaded and ready to fire

Do wear gloves

Do not insert a pencil or other object into the barrel for collection

Do hold the gun by the grp if latent fingerprints are a concern

Do make a weapon safe for transport. If you do not know how, do not assume you can figure it out. ASK.

If the weapon is a revolver, do photograph the cylinder in its position. Mark the chamber that is lined up with the barrel.

Do make a record of the positions of the safety and hammer upon collection and before making the weapon safe.

Do photograph any casings still left in the cylinder.

Do record the state of the firearm.

Do document all information on the firearm including serial number, make, model, and any other markings present.

If a weapon is found underwater, do collect it in a container with enough of the same water is it found in to keep it submerged. DO NOT attempt to dry or clean the weapon.

Do remove the magazine from the weapon and document the number of cartridges loaded.

Do make a note as to which rounds were removed from a magazine and which were removed from the chamber

Do package the weapon in a firearms box and secure it with plastic ties

Do make sure the box the weapon is packaged in is sealed over every open space

Question 33

Firearms identification

Answer 33

a discipline primarily concerned with determining whether a bullet or cartridge was fired by a particular weapon

Question 34

grooves

Answer 34

the cut, or low lying portions between the lands in a rifled bore

Question 35

rifling

Answer 35

the spiral grooves formed in the bore of a fire arm barrel that impart spin to the projectile when it is fired

Question 36

bore

Answer 36

the interior of a firearm barrel

Question 37

lands

Answer 37

the raised portion between the grooves in a rifled bore; the original portion of the bore left after the groove have been imparted into a barrel

Question 38

Caliber

Answer 38

the diameter of the bore of a rifled firearm, generally expressed in hundredths of an inch or millimeters

Question 39

Gauge

Answer 39

the size designation of a shotgun; originally the number of lead balls with the same diameter as the barrel that would equal a pound

Question 40

Breech Face Mark

Answer 40

the rear part of a firearm barrel

Question 41

Extractor

Answer 41

the mechanism in a firearm that withdraws a cartridge or fired casing from the chamber

Question 42

Ejector

Answer 42

the mechanism in a firearm that throws the cartridge or fired casing from the firearm

Question 43

choke

Answer 43

an interior constriction placed at or near the muzzle end of a shotgun’s barrel to control or concentrate shot dispersion

Question 44

Greiss Test

Answer 44

a chemical test used to examine patterns of gunpowder residues around bullet holes