Gunshot wounds and ballistics Flashcards
Interior ballistics (travel within the weapon) can give you what information?
Rifling marks on bullet - class characteristics (make model), individual characteristics (unique to gun). cartridge case (extractor) primer cap (firing pin) fingerprints
if the mass of the bullet is doubled, the energy is doubled - true or false
true
KE = 0.5mass x velocity2
If the velocity of the bullet is doubled, the kinetic energy is doubled - true or false
false - double velocity - quadrupled energy
KE = 0.5mass x velocity2
Which rifling marks indicate the class characteristics of the weapon?
No. of lands and grooves width depth degree of twist direction of twist
Which rifling marks indicate the individual characteristics of the weapon?
imperfections on lands & grooves due to firing/use
Describe the components of small arms ammunition.
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
Jacketed bullets are encased in CuZn, CuNi or Al - why?
prevents the bullet from fragmenting, used in auto-loading pistols and high-velocity rifles.
List the wounding mechanisms of gunshots.
Direct laceration
Shockwaves - may rupture gas-filled organ
Secondary projectiles - e.g. shattered bone.
Discharge gases (contact range)
Entry wound will have inverted skin margin and exit wound shows everting skin margins - true or false
true
exit wound is bigger, since skin everts there are no abrasions at exit site
List some skin surface signs of a gunshot
muzzle imprint (skin kick-back into gun)
Singeing (hot gases)
Smudging/soot
Tattooing (propellant)
Sideways escape of soot-laden gas indicates angled contact range - true or false
false - indicates loose contact range
angled contact range - eccentric soot stain
muzzle against skin = which range of gunshot and what will you see?
muzzle against skin = contact range
soot and propellant seared into margins
anything from contact to intermediate range = ?
near-contact range
few cm
tattooing and peripheral ring of soot staining is seen in near-contact range - true or false
false - NO tattooing but peripheral ring of soot staining can reach up to 20-30cm
soot can be wiped off!
gunshot within arm’s reach = ?
intermediate range (still near enough to be suicide) few cm to 1cm
powder tattooing signifies which range?
intermediate range individual reddish-brown punctate abrasions and/or vital reaction (rim of bruising)
further than arm’s length = ? range
distant range
>1m
at distant range, which skin features will you see?
no flame effects no soot effects no propellant tattooing bullet is on its own. entry wound (central laceration) with marginal abrasion
an elliptical laceration with marginal abrasion, with no soot, flame or propellant effects indicates what?
a shot from distant range (>1m) impacting at an angle other than a right angle
entry wound is circular and exit wound is irregular - true or false
true
diameter bullet on exit
exit wounds have a marginal abrasion - true or false
false - no abrasion on exit; marginal abrasion on entry
No abrasion UNLESS skin pushed against hard surface on exit (bra strap)
entry wound at temple which has extended open the laceration, no tattooing, soot/flame marks around margins
contact range - split by gases
gunshot residues deposit on ulnar side of firing hand - true or false
false - radial side of firing hand
what are gunshot residues made up of?
generally composed of one, two or three of the elements present within the primer.
the bigger the shotgun gauge, the more lead balls within the barrel for 1lb weight - true or false
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
a shotgun power piston will contribute to the wound <20 feet range - true or false
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
what can the shotgun power piston indicate?
manufacturer and gauge
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?
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.
a cherry pink wound margin is seen in which range of shotgun shot?
contact range shotgun wound to torso
carbon monoxide causes the cherry pink colour
contact range shotgun leaves which skin features?
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)
Which range of shotgun wound causes scalloped margins?
shotgun wound distant range causes scalloped margins by 3 feet
no tattooing >3’
Which range of shotgun wound causes satellite holes?
shotgun wound distant range causes satellite holes (fliers) by 4’
cuff of satellite holes by 6’
a loose near-contact gunshot wound shows soot staining on skin. When the soot is wiped away, a burnt hole left = distance?
<3-6’ since flame reached skin
petal marks from power piston = ?
1-3ft = abrasions from petals
<1ft = not yet opened, >3ft folded back
half-formed cuff of satellite holes = ?
~5’ since cuff beginning to form
start to form at 4’ and full cuff by 6’
signs indicative of gunshot suicide include…?
male > females
contact range wound
HV blood splatter on steadying hand
GS residues on firing hand
smudging
deposition of soot on skin (production of gun discharge)
tattooing
propellant grains abrading and embedding themselves into the skin
singeing
burning of the skin and its hairs from hot gases including flame
