Ballistics Flashcards
What is rifling?
Grooves inside the barrel, increasing accuracy by making bullets spin
What are the 2 parts of rifling to look for?
Lands (raised) and grooves (lowered)
What is calibre?
Numerical approximation of diameter of bullet
What is calibre different from?
Diameter ( barrel is deliberately smaller)
3 different types of cartridges
Rimmed, semi rimmed and rimless
Where are firing pin marks found?
Head stamp
What is the head stamp?
The bottom of a cartridge case
What can we tell from spotting?
How far away from the target the weapon and firer were
What class characteristics can you get from breech faces?
None (no known class characteristics)
What is in the middle of an automatic cartridge?
Propellant
What is inside a shotgun cartridge?
Shot and propellant powder
What is unique to a shotgun cartridge?
Plastic wadding
What gun does not have rifling in the barrel?
Shotgun
Who is needed when a firearm/weapon is found?
ARV (armed response vehicle)
What do you need from ARV before handling a firearm?
Red label - confirms weapon has been made safe
What is the general rule for determining distance from shotgun spread?
2.5cm per metre
What can affect the accuracy of determining distance from shotgun spread/ spotting?
Choke (narrows spread, if found, makes distance inaccurate)
What can you get DNA from on ballistics evidence found?
UNFIRED cartridges
How long does GSR stay on hands?
2-4 hours
What is at the bottom of the cartridge?
Primer
Difference of cartridges on revolvers and semi-automatic weapons
Cartridge stays in a revolver;
Cartridges in a magazine in a semi and ejected when fired
How long does GSR stay on the face or hair?
6-12 hours
How long does GSR stay on the surface of clothing?
24 hours
How long does GSR stay on the inside of objects (clothing pockets, cars etc)
Indefinitely
What are the 2 main components that make up GSR?
Antimony and Barium
How relevant is finding a cartridge case and why?
Can be moved very easily, not too relevant and would depend on background information to determine the importance
What does a coroner need to be able to be a coroner?
Either a medical or legal background
What kind of deaths do coroners investigate?
Unknown deaths,
Violent or unnatural deaths,
Deaths in police custody, prison, or another type of state detention
What can be used to help firearm reconstruction?
Laser devices
Strings
Plum Bob and line
Calculator and protractor
NABIS
What is NABIS
National ballistic intelligence service/centre
What to look for with firearm reconstruction?
Path determination
Angle determination
Recognition of holes and marks (trace evidence, visible evidence)
What happens the faster a bullet is fired?
Area of damage smaller
What is external ballistics?
Study of ballistic trajectory
What is terminal ballistics?
Study of behaviours and effects of projectile
What happens the further away a bullet is?
Less accurate shot is due to gravity
What are perforating marks?
Entrance wounds
What do entry wounds look like
Rounded, may burn skin around edge
What do exit wounds look like
Bigger than entry wounds, bevelled outward,
What is powder tattooing?
Close range, powder discharged and damages skin
How to determine which bullet hole was fired first?
Cracks radiating from hole will stop when they encounter another crack
Is it possible to determine calibre by measuring bullet hole
NO
