Estimating Bullet Caliber

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Estimating Bullet Caliber

• By Carra Landrum

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Gunshot Wounds
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Caliber vs. Measurements

• The sample consisted of 73 specimens obtained at
  autopsy
• thirty-seven of .22 caliber
• five of .25
• six of .32
• and twenty-five of .38

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Test Results

• The strongest relationship was observed between
  caliber and minimum diameter.

• Relationship between minimum diameter and maximum
  thickness was also observed

Caliber classification Large caliber.38 Small
caliber.22,.25, .32
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Entrance Wound
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Exit Wound
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Slow Impact
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Fast Impact
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Wound Diameter vs. Bullet Diameter

• The correct classification rate using cross
  validation for
• Large caliber- 86.96
• Small caliber- 93.33
• Caution is suggested when attempting to estimate
  caliber from defects that are not produced from
  the perpendicular entrance of a bullet.

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Results

• overall model is significant
• Even though, many anthropologists argue that
  caliber cannot be determined from entrance wound.

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WHY?

• Trajectory can change the size/shape of entrance
  wound
• Velocity of the bullet can also change the
  size/shape of the entrance wound

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More Test Results

• Caution is recommended in any attempt to
  determine precise bullet caliber from the minimum
  dimensions of the cranial gunshot entrance wound.

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Recover Bullet
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THE END

• QUESTIONS?