Gunshot wounds and ballistics

Question 1

Interior ballistics (travel within the weapon) can give you what information?

Answer 1

Rifling marks on bullet - class characteristics (make model), individual characteristics (unique to gun). 
cartridge case (extractor)
primer cap (firing pin)
fingerprints

Question 2

if the mass of the bullet is doubled, the energy is doubled - true or false

Answer 2

true

KE = 0.5mass x velocity2

Question 3

If the velocity of the bullet is doubled, the kinetic energy is doubled - true or false

Answer 3

false - double velocity - quadrupled energy

KE = 0.5mass x velocity2

Question 4

Which rifling marks indicate the class characteristics of the weapon?

Answer 4

No. of lands and grooves
width
depth
degree of twist
direction of twist

Question 5

Which rifling marks indicate the individual characteristics of the weapon?

Answer 5

imperfections on lands & grooves due to firing/use

Question 6

Describe the components of small arms ammunition.

Answer 6

Bullet - lead alloyed with tin and/or antimony.
Propellant - smokeless powder which burns to produce large volume of gas under pressure. This forces the bullet down and out the barrel.
Primer - shock-sensitive chemical compound which explodes on impact by firing pin, flame secondarily ignites propellant. Primer chemic compounds (lead, barium, antimony) can be found on shooter.
Cartridge case - filled with propellant, expands to fill chamber on discharge

Question 7

Jacketed bullets are encased in CuZn, CuNi or Al - why?

Answer 7

prevents the bullet from fragmenting, used in auto-loading pistols and high-velocity rifles.

Question 8

List the wounding mechanisms of gunshots.

Answer 8

Direct laceration
Shockwaves - may rupture gas-filled organ
Secondary projectiles - e.g. shattered bone.
Discharge gases (contact range)

Question 9

Entry wound will have inverted skin margin and exit wound shows everting skin margins - true or false

Answer 9

true

exit wound is bigger, since skin everts there are no abrasions at exit site

Question 10

List some skin surface signs of a gunshot

Answer 10

muzzle imprint (skin kick-back into gun)
Singeing (hot gases)
Smudging/soot
Tattooing (propellant)

Question 11

Sideways escape of soot-laden gas indicates angled contact range - true or false

Answer 11

false - indicates loose contact range

angled contact range - eccentric soot stain

Question 12

muzzle against skin = which range of gunshot and what will you see?

Answer 12

muzzle against skin = contact range

soot and propellant seared into margins

Question 13

anything from contact to intermediate range = ?

Answer 13

near-contact range

few cm

Question 14

tattooing and peripheral ring of soot staining is seen in near-contact range - true or false

Answer 14

false - NO tattooing but peripheral ring of soot staining can reach up to 20-30cm
soot can be wiped off!

Question 15

gunshot within arm’s reach = ?

Answer 15

intermediate range (still near enough to be suicide)
few cm to 1cm

Question 16

powder tattooing signifies which range?

Answer 16

intermediate range individual reddish-brown punctate abrasions and/or vital reaction (rim of bruising)

Question 17

further than arm’s length = ? range

Answer 17

distant range

>1m

Question 18

at distant range, which skin features will you see?

Answer 18

no flame effects
no soot effects
no propellant tattooing
bullet is on its own.
entry wound (central laceration) with marginal abrasion

Question 19

an elliptical laceration with marginal abrasion, with no soot, flame or propellant effects indicates what?

Answer 19

a shot from distant range (>1m) impacting at an angle other than a right angle

Question 20

entry wound is circular and exit wound is irregular - true or false

Answer 20

true

diameter bullet on exit

Question 21

exit wounds have a marginal abrasion - true or false

Answer 21

false - no abrasion on exit; marginal abrasion on entry

No abrasion UNLESS skin pushed against hard surface on exit (bra strap)

Question 22

entry wound at temple which has extended open the laceration, no tattooing, soot/flame marks around margins

Answer 22

contact range - split by gases

Question 23

gunshot residues deposit on ulnar side of firing hand - true or false

Answer 23

false - radial side of firing hand

Question 24

what are gunshot residues made up of?

Answer 24

generally composed of one, two or three of the elements present within the primer.

Question 25

the bigger the shotgun gauge, the more lead balls within the barrel for 1lb weight - true or false

Answer 25

false the bigger the gauge = smaller no. of balls in that barrel for 1lb weight e.g. 20 gauge = 15mm internal diameter 12 gauge = 18.2mm diameter

Question 26

a shotgun power piston will contribute to the wound <20 feet range - true or false

Answer 26

true - shotgun power piston will strike body at <20' <1ft, not yet opened 1-3ft, abrasions from petals >3ft, folded back >8-10ft, strikes alongside entry

Question 27

what can the shotgun power piston indicate?

Answer 27

manufacturer and gauge

Question 28

A contact range, suicidal shotgun wound to the head is very mutilating due to the gas (comminuted #) and energy of the shot (brains exit via #)... but which side of body gets brunt of shot?

Answer 28

if right-handed, left side gets brunt of shot since torso rotates. This can be confirmed by fine mist/spray of blood onto hand / neighbouring objects which result from the HV shot.

Question 29

a cherry pink wound margin is seen in which range of shotgun shot?

Answer 29

contact range shotgun wound to torso | carbon monoxide causes the cherry pink colour

Question 30

contact range shotgun leaves which skin features?

Answer 30

``` circular entry = muzzle diameter muzzle imprint soot smudging burning or melting of clothes since all the soot, propellant and flame with be caught on clothes cherry pink wound margin (CO) ```

Question 31

Which range of shotgun wound causes scalloped margins?

Answer 31

shotgun wound distant range causes scalloped margins by 3 feet no tattooing >3'

Question 32

Which range of shotgun wound causes satellite holes?

Answer 32

shotgun wound distant range causes satellite holes (fliers) by 4' cuff of satellite holes by 6'

Question 33

a loose near-contact gunshot wound shows soot staining on skin. When the soot is wiped away, a burnt hole left = distance?

Answer 33

<3-6' since flame reached skin

Question 34

petal marks from power piston = ?

Answer 34

1-3ft = abrasions from petals | <1ft = not yet opened, >3ft folded back

Question 35

half-formed cuff of satellite holes = ?

Answer 35

~5' since cuff beginning to form | start to form at 4' and full cuff by 6'

Question 36

signs indicative of gunshot suicide include...?

Answer 36

male > females contact range wound HV blood splatter on steadying hand GS residues on firing hand

Question 37

smudging

Answer 37

deposition of soot on skin (production of gun discharge)

Question 38

tattooing

Answer 38

propellant grains abrading and embedding themselves into the skin

Question 39

singeing

Answer 39

burning of the skin and its hairs from hot gases including flame