1. CRIMINAL INVESTIGATIONS
AMMUNITION/ BALLISTICS
43we
789* n

2. AMMUNITION Cartridge Structure Cartridge Case Primer Head Propellant
Bullet
Blanks- No Bullet

4. Metal Jacket

7. Ammunition

10. AMMUNITION Cartridge Cases Made of Brass Aluminum
30% Copper
30% Zinc
Aluminum
Brass, Plastic and Paper for shotguns

11. AMMUNITION Function of Cartridge Expand and seal chamber
Increase Gas Pressure
Press the case up against barrel
Seals
Springs back to almost same size
Aids extraction

12. AMMUNITION Shapes Straight Bottle neck Tapered Permits more powder
Not in use

13. Ammunition

14. AMMUNITION
Case Head Designs
Rimmed
Semi-rimmed
Rimless
Rebated
Belted

15. 5.56 Centerfire vs. Rimfire

16. AMMUNITION Caliber Nomenclature Rifled barrels
Lands and grooves
Diameter of bore from land to land
Sometimes groove to groove diameter
Bullet diameter

17. Some terminology
Barrel: the metal tube through which the bullet is fired.
Bore: the inside of the barrel, either:
Smooth bore: Shotguns.
Not smooth bore: rifles, pistols.

18. Muzzle: the end of the barrel out of which the bullet comes out.
Primer: volatile substance that ignites when struck to detonate the powder in a cartridge.

22. Types of firearm weapons
Non-rifled: only long
Rifled: short and long

23. What happens?
The holder presses the firing pin which in turn strikes the primer which ignites the powder and produces large amount of hot gas.
Produces very high pressure that fires the bullet forcefully through the barrel leaving the muzzle, and onto the target.

24. Mechanism of injury:
As the missile traverses the body it causes injury by:
Basic contact of bullet and it’s fragments (if present) with the tissue, so larger bullets create bigger damage at the same velocity.
Transferring some of its available kinetic energy to the tissue around it, so increasing velocity greatly increases damage.
It also causes cavitations in the tissue it passes as it accelerates molecules → makes them move centrifugally away from the axis of the bullet.
 Bullets do not typically follow a straight line to the target. Rotational forces are in effect that keep the bullet off a straight axis of flight.

25. SO… Mode of injury depends on the velocity of the missile
-Slow velocity (<340 m/s) speed of sound in air or less
-High velocity (1500 m/s) faster!
High velocity missile causes a shockwave around it’s track → severe disruption → ↑tissue pressure and more damage.
So a 10mm wide bullet may cause a 15mm wide track of damage…

26. Smooth bore weapon (Shotgun):
A gun with a smoothbore that shoots cartridges that contain "shot" or small metal pellets (of lead or steel) as the projectiles.
Ammunition: A shotgun shell(cartridge) may contain one large projectile (called a slug), a few pellets of large shot, or many tiny pellets. Cartridge made of a cylinder fitted into a metal base contains charge of propellant, wads, and shots.
Range is the most important factor, and can be estimated in over half of cases… Close range wounds are severe, but at even relatively short distances, wounding may be minimal.

27. The rifle weapon:
Rifles differ from shotguns in the length of the barrel and the presence of a butt stock.
They fire one projectile at a time through a thicker barrel that has spiral grooves on its inner surface → rotational movement.
They are much more accurate and shoot more powerful cartridges than handguns.
Ammunition: metal cylinder loaded with explosive propellant and bullet.

28. Rifle bullet/pistol bullet

29. AMMUNITION Caliber Specification
U.S. System not consistent or accurate
.303 Savage = .308 bullet
.303 British = .312 bullet
and .308 both fire a .308 bullet
.06 refers to year made

30. AMMUNITION U.S. Caliber Designation Confusing Not accurate
.38 and .357
Difference is length of case and grains of powder

31. AMMUNITION Black Powder Cartridges Designated by: Caliber
Black powder charge
Bullet weight
Examples:
Some smokeless powder cartridges used this designation
.30-30

32. AMMUNITION Metric Designation Bullet diameter Case length
Type of cartridge

33. AMMUNITION Types of Cartridge R = Rimmed SR = Semi-Rimmed RB = Rebated
B = Belted
No letter for rimless

34. AMMUNITION Additional Terms Magnum = Higher velocity than standard
Wildcat = Nonstandard, produced by small entity

36. AMMUNITION Head Stamps All cases have stamps on bases
Imprinted for Identification Purposes
Letters
Numbers
Symbols
Trade names

38. AMMUNITION Head Stamps (Cont.) Civilian made with manufacturers symbol
Military made with initials or codes
Year of manufacturing
Match/nm = military match grade ammo
+ = NATO
+P or +P+ = High Pressure

39. AMMUNITION Bullet Powder Weights Grain = weight not granules
1 oz. = grains
1 grain = grams
Bullet and powder weights measured in grains

40. AMMUNITION Primer (Cont.) Non-corrosive/Non-mercuric Lead Styphnate
Barium Nitrate
Antimony Sulfide
Most U.S. primers contain all three
*Detection of these compounds provides bases for GSR

41. AMMUNITION Primers (Cont.) Rimfire Ammo No primer assembly
Primer chemical is in rim

42. AMMUNITION Propellants Black Powder Charcoal is fuel
Sulfur
Potassium Nitrate
Charcoal is fuel
Nitrate supplies oxygen
Sulfur creates density

43. AMMUNITION Propellants – Black Powder When powder burns
Gas = 44%
Residue= 56%
Residue appears as dense white smoke

44. AMMUNITION Smokeless Powder 1884 Vieille – French Chemist
Nitrocellulose
Used EtOH/Ether
Rolled into sheets
Cut into flakes
Single base

45. AMMUNITION Smokeless Powder (Cont.) 1887 – Alfred Noble
Nitrocellulose and Nitroglycerine
Rolled and cut into flakes
Double base

46. AMMUNITION Ball Powder Winchester 1933 Nitrocellulose dissolved
Formed into balls
Different diameters
Appears uniform round, black spheres or ovals
Reflective surface
Flattened round
Irregular
Flattened chips
Wide variation between round and flat

47. AMMUNITION Powder Grains Disk Flake Cylinder Uncoated (Greenish color)
Coated w/Graphite (shiny black)

48. Ammunition Powder (continued) Powders burn at different rates
Gases and unburned grains are discharged upon firing
Grains can be found in clothing and skin

49. Ammunition Bullet Originally lead spheres Musket vs.. Rifle
Minnie ball (Capt.. Minnie, French Army)
Modern bullets
Lead
Metal-jacketed

50. Ammunition Bullets Various shapes Round Hollow point Semi-wadcutter

52. Ammo performance-Handguns
Cartridge
Bullet gr.
Velocity
Ft-lbs
.380 95
955
190
9mm
124
1299
465
.40 S&W
155
1140
447
.45 ACP
230
855
405
.38
158
755
200
.357
1235
535
.44 mag
240
1350
971

53. Ammo performance-Rifles
Cartridge
Bullet gr.
Velocity
Ft-lbs
.223 55
3150
1218
5.45x39 53
2985
1053
.270
130
3060
2702
.30-30
150
2390
1902
.308
2750
2520
.30-06
2740
2500

55. Bullet Comparison Class characteristics Number of lands and grooves
Diameter of lands and grooves
Width of lands and grooves
Depth of lands and grooves
Direction of rifling twist
Degree of twist

56. Bullet Comparison Individual Characteristics
Imperfections on lands/grooves
Score the bullets
Jacketed bullets, more pronounced
Are peculiar to each firearm

60. Bullet Comparison Factors impacting Ind. Characteristics Rusted barrel
Jacketed/unjacketed
Velocity/pressure
Bullets vary from lot to lot

61. Bullet Comparison Additional markings Compositional Analysis
Skid marks
Shaving
Compositional Analysis
Fragments are recovered
SEM-EDX
Comparison between suspected guns bullets and recovered fragments

63. Bullet Comparison Base markings Imprinted from propelled powder grains
Most evident in bullets w/lead base
Shorter barrel, deeper marks
Different forms produce different marks
Spherical=circular pits
Disk=circular imprints
Black powder=peppered

66. Bullet Comparison Additional factors
Bullets fired in wrong caliber weapon
Decomposed bodies (Study after 66 days)
Nylon clad-unaffected
Aluminum-mildly affected
Lead bullets, recovered from
Brain, chest cavity, abdomen-mild tarnish
Fat, muscle-severe oxidation-impaired match
Copper alloy-severe degradation

67. Bullet Comparison Surface analysis of bullet DNA typing
Non-organic material
Tissue analysis
DNA typing

68. Cartridge Case Comparison
Comparison “MAY” make ID possible
Type
Make
Model
Test and evidence cartridges compared
Use same brand and lot
Ammo consistency

69. Cartridge Case Comparison
Markings=imprints or scratches
Magazine marks
Breech block marks
Firing pin marks
Size,shape, and location of;
Extractor and ejector marks
Flute marks

70. Ballistics Ballistics=Study of motion of projectiles Internal External
Terminal
Wound ballistics

71. Ballistics Forces K.E.=1/2mv2 Velocity place larger role in force
Doubling mass, doubles force
Doubling velocity quadruples force
Energy transfer/loss

72. Ballistics Energy Loss/transfer Amount of K.E. upon impact
Angle of yaw upon impact
Caliber, construction, shape
Density, strength, elasticity of tissue

73. Ballistics-Structural Mechanics
Elasticity (Stretching)
Shearing
Compression
Cohesiveness
Tensile strength
Density

74. Ballistics Movement through body Crushes/shred tissue in path
Flinging, radially, surrounding tissue
Temp. cavity several times (12) size of bullet
Lasts 5-10 msec
Pulsates, contractions and collapse
+/- pressure sucks in bacteria/foreign materials

75. Ballistics

76. Ballistics Temporary/Permanent Cavity
Max diameter of temp cavity is proportional to amount of kinetic energy lost
Occurs at maximum yaw or fragments
Yaw continues until Cg is forward or approx 180 degrees rotation
Size of cavity is determined by amount of K.E. lost by bullet
Size of cavity is determined to a degree by cross section of round

78. Ballistics Temporary/Permanent Cavity (cont.)
Compression, stretching, tearing of tissue
Handguns-Damage to area hit by bullet, very little collateral damage
Rifles-Radial damage to nerves, tissue, vessels, organs not struck by bullet
Damage related to density, elasticity and cohesiveness of tissue
Muscle vs. Liver vs. Lung

79. Ballistics

80. Ballistics Energy loss along wound track Not uniform
Changes and variations occur due to;
Angle of yaw
Change in density of tissue
Change in structural dimension of bullet (mushrooms)
Fragmentation amplifies effect
.223 marked yaw at 12cm
Major frag/tissue disruption at 15-25cm

81. Ballistics

82. Ballistics Critical velocity At or above 2625-2953 ft/sec (FMJ)
At or above ft/sec (expanding ammo)
Tissue damage more severe
Supersonic flow = strong shockwaves
Shockwaves travel through body
Damage is times larger
Due to higher amount of K.E. loss

83. Ballistics Critical amount of K.E. loss Wounds are more severe
Exceeds elastic limits
Organ bursts
Projectile does not have to be near organ

84. Ballistics Critical amount of K.E. loss-Head Special case
Cranial cavity is a closed, rigid structure
1% elasticity
No place for energy to disperse
Results in bursting injuries (high velocity)

85. Ballistics Temporary cavity structure FMJ Hunting rifle round
Shotgun pellet

86. Ballistics Temporary cavity size Permanent Cavity size
10-12 times diameter of bullet
High K.E. loss times bullet
Permanent Cavity size
Handgun=smaller than round diameter
High velocity=size of bullet
Unless Elastic limit of tissue is reached=large irregular tearing wound track.

87. Case Study
This case involved a barroom shooting.  The incident went something like this:

88. Case Study
Guy No.1- "Hey man, my quarters were up next!!   I've got the next game on that pool table!!"

89. Case Study
Guy No. 2- "Man you’re crazy!  I've had my quarters up there for over an hour!"

90. Case Study
Guy No. 1- "Oh yeah? Well not only are my quarters up next but your breath stinks too!!!"

91. Case Study
Guy No. 2- "You son-of-a-XXXXX!!!!! I'm gunna kill you!!!"

92. Case Study
Me- "Now guys, calm down it's only a pool game; it's only a quarter."

93. Case Study
Guy No.1 pulls out the Llama 45 auto below and points it at Guy No. 2.

95. Case Study
In a drunken stupor he fires a single shot at Guy No. 2, missing him and hitting me right between the eye's with this 45 AUTO, 230 grain full-metal-jacketed bullet.

97. Case Study
At the same time the pistol ejects the 45 AUTO cartridge case below into the corner pocket of the pool table.

100. Case Study
Guy No. 1 and Guy No. 2 run out of the bar get in a car and go home.   They tell mom they have been to the movies, hide the gun under their bunk bed and go to sleep.

101. Case Study
Meanwhile back at the bar, a riot has ensued because the other guys with quarters on the table are really p off because the spent case has jammed the pool table.  Order is finally restored when county police detectives clear the table.  

102. Case Study
My cold lifeless body is taken to the Medical Examiners Office for the 9 AM autopsy.

103. Case Study
Guy's No. 1 and 2 are later roused from bed by Detectives and the pistol, it's magazine, and four 45 AUTO cartridges are recovered from under the bed.

104. Case Study
The pistol, magazine, live ammunition, spent case, and bullet are later submitted to the lab for analysis.

105. Case Study
Although my ex-coworker is all but overcome with grief, he manages to set aside his personal ties to the case and conducts the required analysis in a totally professional and unbiased fashion.

106. Case Study
First course of business is to examine the pistol, which is found to be in perfect working condition.  The pistol is test fired in the water tank and standards from the pistol are compared to the spent case from the pool table and bullet from my head.

107. Case Study
The results of which are the match seen below.

109. Case Study
Breech Marks: Standard from pistol (left) compared to the spent case from the bar (right).

111. Case Study
Bullet land impression comparison: Standard (left) compared to "my" bullet (right).

113. Case Study
By the way, Guy 1 "walks" when his brother testifies that I started the fight by stealing his brother's hot wings.

114. Case Study
They really do have the best hot wings in town!!!

115. AMMUNITION Primers Shapes Purpose Fulminate of mercury Berdan Boxer
Anvil built in case
Boxer
Anvil built in
Purpose
Fulminate of mercury
Causes corrosion