1. What is ballistics? Give 3 examples of how ballistics is used in forensic science.

2. Forensic Science: Fundamentals & Investigations, Chapter 17
Introduction
Ballistic evidence helps explain:
What type of firearm was used.
The caliber of the bullet.
The number of bullets fired.
Where the shooter was.
Whether a weapon was fired recently.
If a firearm was used in previous crimes.
Forensic Science: Fundamentals & Investigations, Chapter 17

3. History of Forensic Firearm Identification
1835 – London, England. Mold mark used to make bullet from molten lead used as evidence in homicide case
1863 – Examination of the bullet type and design used to shoot Gen. Stonewall Jackson showed he was shot by one of his own men
1879 – Minnesota. Rifling marks from a revolver used in court to differentiate two revolvers
1925 – The comparison microscope is developed by Philip Gravelle
Please refer to the document titled “History of Firearm Identification” by Dr. James Hamby included on the disk for more information and discussion topics.

4. Forensic Science: Fundamentals & Investigations, Chapter 17

5. Forensic Science: Fundamentals & Investigations, Chapter 17

6. Ammunition
bsapp.com

7. Forensic Science: Fundamentals & Investigations, Chapter 17
Parts of a Cartridge
Bullets =projectile Case (casing)=holds propellant Cartridge=Bullet+Case
Forensic Science: Fundamentals & Investigations, Chapter 17

8. bsapp.com

9. bsapp.com

10. bsapp.com

11. Three Main Shapes
bsapp.com

12. Round Nose Maximum penetration Cheapest shape to manufacture
Easily loads into chambers
bsapp.com

13. Hollow Point Spreads or mushrooms on impact
Causes additional damage to target
Inhibits penetration
bsapp.com

14. Wad Cutter Used exclusively as a practice load Minimizes penetration
Rips a hole in target paper which is visible by the shooter
bsapp.com

15. Three Basic Compositions of Bullets
Lead
½ Jacketed
Jacketed (Full metal jacket)
bsapp.com

16. Lead
Cheap
Dense
Soft
Easy to mold
bsapp.com

17. ½ Jacketed
A lead bullet coated with copper half way up the exposed portion of the bullet
Used primarily for
hollow points
Copper improves
exit velocity
Lead promotes mushrooming
bsapp.com

18. Jacketed A lead bullet completely coated in copper
Copper improves exit velocity
Used to hold the shape of the bullet in an effort to maximize penetration
bsapp.com

19. Caliber of the Cartridge
Caliber is a measure the diameter of the cartridge in hundredths of an inch.
Common calibers include .22, .25, .357, .38, .44, and .45.
Why should the caliber of ammunition match the firearm that shoots it? If they do not match, what could go wrong?
If they don’t match – the bullet could get stuck or possibly cause the gun to explode/get extremely hot/backfire.
Forensic Science: Fundamentals & Investigations, Chapter 17

20. Firing Sequence
bsapp.com

21. Pull the Trigger and . . .
Trigger is pulled, causing hammer to move backwards
The hammer strikes the primer. This causes a spark.
The powder is then ignited causing an explosion.
This explosion starts the bullet down the barrel of the gun
bsapp.com

22. Down the Barrel
Rifling inside the barrel causes the bullet to spin, increasing accuracy
bsapp.com

23. Out of the Barrel
5.This rifling causes the marks known as lands and grooves.
bsapp.com

24. Bullet Analysis & Comparison What are some characteristics used to identify & compare bullets?
bsapp.com

25. Striations
bsapp.com

26. bsapp.com

27. bsapp.com

28. bsapp.com

29. bsapp.com

30. Matching Procedure Fire bullets from a suspected weapon
With the aid of a comparison microscope, compare these “test fires” to the suspected bullets
Striations must be identical for a positive match
bsapp.com

31. Comparison Microscope
Two scopes- One Field
bsapp.com

32. bsapp.com

33. bsapp.com

34. What happens to a bullet when it hits a target?
Most bullets tend to mushroom when they hit a target.
Some bullets nearly disintegrate.
Left are bullet fragments from a ½ jacketed hollow point.
bsapp.com

35. Not all bullets mushroom the same
Not all bullets mushroom the same. A lot depends on the speed and shape of the bullet, and the characteristics of the target.
bsapp.com

36. bsapp.com

37. Some more bullets recovered after firing
The striations from the rifling are still visible
bsapp.com

38. Forensic Science: Fundamentals & Investigations, Chapter 17
Gunshot Residues
Chemical testing often can detect gun shot residue even if removal is attempted.
What does this mean for investigation?
Forensic Science: Fundamentals & Investigations, Chapter 17

39. Forensic Science: Fundamentals & Investigations, Chapter 17
Databases
Like fingerprints, there is a federal database for firearms used in previous crimes – NIBIN (National Integrated Ballistics Network).
Forensic Science: Fundamentals & Investigations, Chapter 17