1. Firearms and Ballistics

2. Revolver 3. Semi-Auto Pistol 4. How a gun works 5. Four Components of Ammunition

Primer

• Rimmed or Centerfire

Cartridge Case or Shotshell

Propellant

Projectile(s)

6. Ammunition 7. Ammunition 8. PREMIUM LOAD with SHOTCUP Pellets donot contact bore 9. 10. 11. Some problems 12. Stable vs. InstableProjectile Flight 13. Rifling 14. 15. 16. 17.

When a firearm is manufactured, the individual parts are made with tools that are in a constant state of change

As a result,no two guns will leave the same marks on the ammunition components

The marks found on bullets are sometimes referred to asstriations

18. 19. 20. The match on the bullet 21.

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22. 23. Gunshot Residue 24. Source of Gunshot Residue

Firing a weapon may cause microscopic particles of primer residue and gunpowder to be deposited on the hands of the shooter

The higher the caliber, the more GSR depositied on hands

.22 caliber rim-fire cartridges will sometimes not show traditional GSR particles

25. Primers

Lead Styphnate

• Primary explosive

Barium Nitrate

• Oxygen Source

Antimony Sulfide

• Fuel

26. Formation of the Particle

Upon detonation, the compounds of the primer vaporize, mix and then condense back into particles

The result: what was once three separate particles have become one particle made up of lead, barium and antimony

27. Inside a GSR kit

Each GSR kit contains

• Instructions

• A pair of rubber gloves

• Labels

• Two sample vials

Each vial contains adhesive coated aluminum stub mounted on the base of a rubber stopper

Stub pressed and lifted on the surface being sampled

• Hand

• Face

• Clothing

28. The Examination

Look for particles with the proper morphology and size

Look for particles which contain all three components of the primer

• Lead (Pb)

• Barium (Ba)

• Antimony (Sb)

29. Scanning Electron Microscope

Magnification ranges from 10x to 10,000x

Allows you to visualize GSR particles and gives you information on the elemental makeup of the particles

30. GSR Particle on the SEM 31. Positive: What does it mean?

The individual fired a weapon

The individual handled a weapon right after it was fired

The individual was very near when the gun was fired

The individual touched a surface that had GSR on it.

Etc, etc, etc.

32. Negative: What does it mean?

The individual did not fire a weapon

The individual washed their hands

The sample was collected after the recommended 4-6 hour time window

The individual was wearing gloves when they fired the weapon

Etc, etc, etc.

33. Lead Poisoning 34. Bullet Trajectory 35. Projectile Penetration

Three Possibilities

• Projectile is stopped by impact without penetration

• Projectile will penetrate the object without exiting

• Projectile will pass through object (Perforate)

36. Definitions

Penetration

Penetration is when a projectile enters but does not exit. Not to be confused with Perforation

Perforation

Perforation is when a projectile passes through and through. Not to be confused with Penetration

37. Penetration and perforation The Bullets effect on sheet metal at increasing angles 38. Critical Angle and Deflection 39. Critical Angle and Deflection 40. 41. 42. 43. Trajectory reconstruction using lasers 44. Laser trajectory at night 45. Shotgun Pellet Patterns In General. For every 1 across = 1 Yard from Muzzle7 Muzzle to Target = 7 Yards 46. Pellet Pattern Diameter vs. Range Orthogonal Impacts d d d 47. Non-Orthogonal Pellet Patterns sin -1(d/D) = incidence angle 48. Orthogonal Strikes No. 4 Buck 12-ga. d = 7 in. 49. 45 0Incident Angle with No. 4 Buck, 12 ga. d = 7 in. d/D = 0.67 Sin -1= 42 0 SameRange as previous shot 50. LEFTvsRIGHT 51. RIFLING TWIST DETERMINATION from RICOCHET MARKS on SMOOTH, HARD SURFACES The Chisum Trail 52. 230-gr. .45 Auto FMJ-RN Incident Angle = 10 0 Surface = Smooth SteelRicochet Angle = 1.4 0 13 0 profile views 53. Three 50-gr. FMJ .25 Automatic Bullets Ricocheted from a Hard, Unyielding Surface after Low (less that 5 0 ) Incident Angle Impacts 54. Cartridge Case Ejection Patterns

Each Firearm is Different

• Ammunition

• Ground Surface

Shooters Stance Does Not Matter

• Weaver vs. Prone

• Grip doesnt matter

How the Gun is Held Matters

55. Ejection Patterns X 56. Bullets and Glass 57. BB Impact 58. 59. 60. 61. 62. Effects of Projectiles on Common Materials

Laminated

Glass

63. 64. 65. Laminated Auto Glass 66. What else can be matched? 67. 68. Extractor and Breech 69. 70.