1. Ballistics
Frank
&
Tony

2. History
Who were the first to use guns and/or gunpowder?

3. History China= 800s, used gunpowder
But ancient Greek writings of 200s reference “shooting powder”

4. History First Gun Load gunpowder down a tube
Put a projectile down tube
Ignite powder with wick

5. History
Oldest pic of around 1326
Vase-shaped barrel

6. Modern-day guns

7. Grooves and Lands put spin on bullet

8. Lands and Grooves create striations on bullet

9. No two rifled barrels, even those manufactured in succession, will have identical striation markings
Slight imperfections during rifling

10. Caliber
What is caliber?

11. Caliber Diameter of gun barrel between opposite Lands
Recorded in hundredths of inch or millimeters
Ex: .22 inch, .38 inch, 9mm
NOT exact
.38 Cal may have barrel range of

12. Bullet-Gun Connection
Need bullet from crime scene and suspected gun
Shoot gun to recover undamaged bullet

13. Bullet to Bullet to Gun Comparison

14. Things to compare Number of Land and Groove Markings
A 5 Land/Groove bullet does not come from a 6 land gun
Width of Lands and Grooves
Direction of twist
A right twist bullet can’t come from a left twist barrel
Striation specifics

15. FBI General Rifling Characteristics Files

16. Problems
Perfect Land/Groove
Markings
Reality:Frags, Grit, Rust

17. Why can’t we get striation markings from shotgun ammunition?

19. Shotgun Ammunition
Weigh and measure diameter of shot pellets

20. Shot

21. Shotguns and Gauges
What is a shotgun’s gauge?

22. Gauge Diameter of barrel Ex. 12 gauge=diameter of 0.730 inches

23. Ballistic Mechanics

24. Ballistic Mechanics
Trigger Pulled
Activates Firing Pin
Hits Primer

25. Ballistic Mechanics 4. Gunpowder ignited
5. Gases propel bullet through barrel
6. Spent casing bashed against breechblock
Striations breechblock

26. Ballistic Mechanics
7. Spent Cartridge removed from barrel by an Extractor
8. Spent Cartridge thrown out of gun by the Ejector
Both are sources for markings!

27. Ammunition

28. - Semi-Automatic Rifle or Shotgun

29. Databases
IBIS
DRUGFIRE

30. Gunpowder Residue
Why is it important to know the range of gun to victim?

31. Gunpowder Residue Suicide (-at long range?)
Self-defense (-but shot close & side of head?)

32. Gunpowder Residue

33. Gunpowder Residue

34. Shot Distance Determinations
Need victim clothing with bullet holes
Need the weapon
Need identical clean clothing
Need to fire shots at various distances at clean clothing to reproduce markings on clothes

35. Shot Distance Determinations
Muzzle fire burns or melts cloths
Concentrated burn marks and shot residue immediately around hole
Close Range, less than 6”

36. Shot Distance Determinations
Halo of smoke-soot around hole
Shot 12” away

37. Shot Distance Determinations
Scattered specks of shot residue with less soot around hole
About 18” Away

38. Shot Distance Determinations
Weapon fired more than 3 feet from subject, no visible powder on subject
Can do a ”Bullet Wipe”
Around hole will be carbon, dirt, lubricant, primer residue and lead from bullet passing

39. Determining the presence of powder residue on clothes
Greiss Test
Press a treated photo paper against questioned surface with an iron
Nitrate residue stuck and chemically enhanced
Lead Test
Spray Sodium Rhodizonate and then acids
Residue develops blue-violet color

40. Determining the presence of powder residue on hands
Old School: Nitrate Test on hands
Wax hands, lift wax
Stain wax with diphenylalanine
Get blue color
Problem with false positives!

41. Determining the presence of powder residue on hands
Detect:
lead styphnate
barium nitrate
Antimony sulfide
Swab hands to collect residue

42. Determining the presence of powder residue on hands
Atomic Detection Devices
Neutron Activation Analysis
Atomic Spectrophotometry
VERY Expensive technology!

43. Determining the presence of powder residue on hands
Collect samples from hands for Scanning Electron Microscopy
Problem with hours to scan for particles

44. Determining the presence of powder residue on hands
Overall Problem?

45. Determining the presence of powder residue on hands
Intentional and Unintentional washing off of residue
Have a 2hr window to get accurate results.

46. Serial Numbers
Functions and Problems?

47. Serial Numbers Stamped into metal History of individual gun ID Owner
Track crimes committed
Can file down number!

48. Serial Number Restoration
Stamped metal area weaken
When acid is applied to filed area, the strained area will burn at a faster rate than surrounding metal

49. Firearm Collection
NEVER PUT A PENCIL DOWN BARREL AREA!
WHY?

50. Don’t want to disturb powder
Don’t want to disturb rust and dirt
Will destroy or alter future striation marks
Unload gun and handle by trigger guard and grip area

51. Ammo Collection Protect striations
Bullets in wall may become more damaged if removed improperly.
Wrap in paper
Put into pill box

52. Bullet Trajectory Analysis

53. Bullet Trajectory Analysis

54. Bullet Trajectory Analysis