firearms and toolmarks

Question 1

what is a firearm

Answer 1

device (assembly of a barrel and action) from which a projectile is propelled by combustion

Question 2

handguns

Answer 2

pistol
revolver
derringer

Question 3

long guns

Answer 3

rifles
shotguns

Question 4

pistol

Answer 4

handgun
a firearm designed to be held and fired with one hand
pistol
handgun in which the chamber is integral with the barrel
semi automatic pistol
handgun in which ammunition is fed by a magazine and the ammunition is fired and ejected with each pull of the trigger

Question 5

derringer

Answer 5

generic term applied to many variations of ams one two or even four shot pistols
Henry deringer

Question 6

revolver

Answer 6

firearm, usually handgun with a cylinder having several chambers so arranged as to rotate around an axis
discharged ammunition (cartridge cases) must be manually removed by the user

Question 7

rifle

Answer 7

a long gun designed to be shot from the shoulder with a rifled bore
multiple different action types
semi automatic automatic and bolt

Question 8

shotgun

Answer 8

a long gun designed to be shot from the shoulder typically having a smooth bore designed to fire shotshells

Question 9

ammunition cartridge (live ammunition)

Answer 9

4 main components,
bullet/projectile
cartridge case
hols the components
propellant/powder
burns and produces pressure that propels bullet
primer ignites powder

Question 10

parts of a cartridge

Answer 10

cartridge head
base of the cartridge case which contains the primer and location of the head stamp
headstamp
numeral letters and symbols stamped into the head of a cartridge case or shotshell to identify the manufacturer caliber gauge or other additional information

Question 11

rimfire

Answer 11

primer contained In the rim around edges of head of cartridge case

Question 12

centerfire

Answer 12

primer contained in the center of the head of the cartridge case

Question 13

bullet types

Answer 13

full metal jacket (ball)
jacketed hollow point (JHP)
semi jacketed hollow point (SJHP)
lead hollow point (LHP)
semi-wad cutter (SWC)
wad cutter (WC)
range papers

Question 14

caliber

Answer 14

for the firearm
approx diameter of the highest points of the inside of the barrel
typically expressed in hundredths of an inch or mm .354
for ammunition
numerical term without decimal point included in a cartridge designation to indicate the nominal (approx) bullet diameter, 38, 9mm

Question 15

cartridge designation

Answer 15

term used to designate the specific cartridge for which a firearm is chambered
38 SPecial, 357 magnum

Question 16

shotshell ammunition

Answer 16

hull/casing
projectile (shot or pellets)
wad column
powder
primer
guage instead of caliber

Question 17

cycle of fire

Answer 17

loading (chambering)
locking
cocking
firing
unlocking
extraction
ejection

Question 18

toolmark

Answer 18

created when two objects come into contact
harder object of two will leave a mark on softer object
in firearms, gun is tool
barrel leaves marks on bullet
breech fact, extractor, ejector, chamber, firing pin/aperture

Question 19

two types of tool marks

Answer 19

striated
impressed

Question 20

striated

Answer 20

marks (generally microscopic) on surface of an object caused by combination of force and motion where the motion of the tool is approx parallel to plane being marked
scratch

Question 21

impressed

Answer 21

marks on surface of object caused by force where tool is approx perpendicular to the plane
stamp

Question 22

bullet and barrel

Answer 22

barrels of pistols revolvers and rifles are typically rifled and contain general rifling characteristics
number width and direction of twist of the rifling grooves in a barrel of a given caliber firearm
land is raised groove is dent
as bullet travels down barrel the lands and grooves impart markings onto bullet
these are unique markings that are used to identify a particular firearm

Question 23

class characteristics

Answer 23

diameter of bullet, caliber
number of lands and grooves
twist of
width of lands and grooves

Question 24

areas that mark cartridge

Answer 24

extractor breech fact firing pin, firing pin aperture, ejector
unlocking begins after firing
unlocking continues as the pressure pushes slide rearward, while cartridge head slams back imparting marks on the softer material (breech face)
the rearward movement causes barrel to drop in
while still partially in chamber, cartridge case also drops down causing the shearing of the metal that has flowed into firing pin hole
softer metal cartridge case is being marked after firing by the breech face, firing pin, extractor, and ejector

Question 25

doc and firearm

Answer 25

when firing ammunition the firearm is the tool and will leave marks on the cartridge case
tool marks are individual and unique so they can be used as a finger print for that particular firearm

Question 26

class characteristics

Answer 26

measurable features of a specimen which indicate a restricted group source
they result from design factors and are therefore determined prior to manufacture
types of breech face marks, firing pin shape, caliber

Question 27

individual characteristics

Answer 27

marks produced by the random imperfections of irregularities of tool surfaces
random imperfections or irregulars produced incidental to manufacture and or caused by use corrosion or damage
unique to that tool and distinguish it from all other tools

Question 28

types of breech face

Answer 28

parallel, arch, crosshatch, circular, granular, smooth

Question 29

ejector marks

Answer 29

various ejector shapes
differ ejector marks

Question 30

types of anaysis

Answer 30

render safe
assault weapon
serial number test fire
full auto determination
bullet/path impact assessment
evidence collection
nibin
type and caliber
comparison
distance

Question 31

render safe

Answer 31

anything which cannot be cleared or checked by officers in field
muzzle loaders and black powder firearms
do not manipulate safeties buttons levers unless to unload
by use of specialized tools a safe range and photography
firearms which are damaged unfamiliar or have special handling concerns unloaded in the laboratory