Terminal Ballistics and Wound Morphology

Defined as the study of projectile impact on targets involving solids and liquids.
Divided into two sub-fields: penetration potential and wound ballistics (effects on living tissue).

Earth (Barringer Meteor Crater, Arizona): * Projectile: Nickel / Iron material, $50\,m$ diameter. * Impact: Velocity of $11000\,m/s$ . * Result: Crater measuring $1200\,m$ in diameter and $200\,m$ in depth.
Space: Research by the University of Kent on metal surfaces from the Curnneon Retrievable Carrier.

Projectile Behavior: Can disintegrate, bend, deform, or penetrate/perforate the target.
Kinetic Energy ( $KE$ ) Transfer: Used to breach cloth and skin. If $KE$ is fully exhausted, the bullet is absorbed; if partially used, the bullet passes through the body.
Entry vs. Exit: * Entry holes are often smaller than the bullet diameter due to skin extensibility and the "drill" effect of spin-stabilized flight. * Exit holes are larger because the bullet loses stability in denser media (body tissue) and begins to "wobble," increasing its cross-sectional area.

Injury Phases: Transition from a narrow channel ( $NC$ ) to a temporary cavity ( $TH$ ) as the bullet rotates into a position perpendicular to travel ( $BQ$ ).
Wounding Factors: Determined by the cross-sectional area of the bullet and secondary missiles generated from bullet fragmentation.
Design Variations: * Fully-jacketed bullets resist deformation. * Soft lead hollow point bullets are designed for Mushrooming, a controlled expansion that increases diameter to maximize energy delivery and minimize over-penetration dangers to bystanders. * Mushroomed bullets present forensic challenges by obscuring GRC information on folded surfaces.

Momentum Calculation: A $140\,grains$ ( $0.02\,lb$ ) rifle bullet at $3000\,ft/sec$ carries a momentum of $0.02 \times 3000 = 60\,lb\,ft/sec$ .
Impact Effect: For a $200\,lb$ man, the conservation of momentum $(200 + 0.02) \times V = 60$ yields a velocity ( $V$ ) of $0.2999\,ft/sec$ .
Energy Comparison: The resulting Kinetic Energy of $\approx 0.27\,ft\,lb$ would only lift a $200\,lb$ man by $0.016\,inch$ .
Conclusion: The concept of a person being thrown backwards by bullet impact is a "sensationalization by the entertainment industry."

Kevlar: A lightweight, flexible material used in vests; it is susceptible to UV light and loses ballistic effectiveness when wet.
Polyethylene (Spectra): An alternative fiber for body armor.
Armor Levels: * Levels I - IIIa: Soft body armor (Kevlar) capable of stopping most handgun ammunition. * Levels III - IV: Rigid plates made of Ceramics or Polyethylene designed for stronger ammunition.