Forensic analysis Part 2

Question 1

What is a bullet

Answer 1

A projectile below 20mm in diameter that is fired from a barrel weapon, anything above and it is a shell
Normally have a lead core

Question 2

Bullet

Answer 2

Lead antimony alloy core
97% lead and 3% antimony
The antimony reduces the malleability of the alloy and makes the lead core less easily deformed
Most bullets are fully or semi-jacketed to protect the lead core
Unjacketed bullets are still in use however

Question 3

Jacketing

Answer 3

Jacketing stops rifling drag in the barrel
Lead deforms really easily under acceleration
A brass jacket improves rifling pick up, and reduced acceleration deformation

Question 4

Unjacketed

Answer 4

Lead alloy only - may be round, flat or hollow nosed
Cheap
Low muzzle velocity
- low penetration
- high impact deformation
- Prone to rifling smear at high muzzle velocities

Question 5

Semi-Jacketed

Answer 5

Includes soft point, hollow point, and polymer tipped
Usually a bright brass jacket
- with a lead alloy core

Less impact deformation than unjacketed
- low penetration
- high energy transfer

Question 6

Fully-Jacketed

Answer 6

Full metal jacket
- may still have exposed lead
Usually a bright brass jacket
- with bonded or partitioned lead alloy core
Excellent penetration with relatively low energy transfer
- High stability
- High energy retention

More expensive

Question 7

Internal bullet structure

Answer 7

Solid lead alloy core is the most common internal structure
A partitioned core mushrooms and retains some of its core on impact

Question 8

Bullet statistics

Answer 8

Handgun bullets - 200 - 400 m.s-1
Rifle bullets - 300 - 1500 m.s-1

Question 9

Recovering bullets

Answer 9

Fired bullets can be found in any condition from near pristine to completely fragmented
Even the most damaged bullet can yield data