Terminal Ballistics


BTG Research

Though three distinct wounding mechanisms (permanent cavity, temporary cavity, and ballistic pressure wave) are described in the wound ballistics literature, they all have their physical origin in the retarding force between bullet and tissue as the bullet penetrates. If the bullet path is the same, larger retarding forces produce larger wounding effects and a greater probability of rapid incapacitation. By Newton's third law, the force of the bullet on the tissue is equal in magnitude and opposite in direction to the force of the tissue on the bullet. For bullets penetrating with constant mass, the retarding force on the bullet can be determined by frame by frame analysis of high speed video of the bullet penetrating a suitable tissue simulant such as calibrated 10% ballistic gelatin. Here the technique is demonstrated with 9mm NATO bullets, 32 cm long blocks of gelatin, and a high speed video camera operating at 20,000 frames per second. It is found that different 9mm NATO bullets have a wide variety of potential for wounding and rapid incapacitation. This technique also determines the energy transfer in the first 15 cm and/or first 30 cm of tissue, which are important parameters in estimating the probability of rapid incapacitation in some of the ARL/BRL models. This method predicts that some 9mm bullets have a much higher probability of rapid incapacitation than others and the rank ordering of bullet effectiveness is in agreement with other studies.

Within the military community, the uses for projectile wound data can be grouped into two related, but different categories: [I1 Operational - quantitative and functional in nature; domain of the weapons analyst. 121 Medical - somewhat more qualitative in nature and treatment oriented Although both areas depend on an understanding of the physiological and mechanical phenomena behind the body's response to penetrating wounds, the needs and applications of the analyst and plhysician are quite different. While there is common ground in the two uses of wound information, the nature and measure of what is important are different. Therefore, the respective wound ballistics methodologies used by the two communities need not be and are not the same.

The NATO and US Army Handbook of Human Vulnerability

  • The NATO and US ARMY Handbook on Human Vulnerability (or newer Total Body Model) for penetrating projectiles shows very little differential on probability of one shot stopping power of 22LR/9mm/45.

  • The amount of energy at impact to incapacitate or kill a man is about 40 lbs minimum, i.e. energy dump.

  • Low probability hits to the major nervous system, skeleton, or circulatory system which inflict very quick incapacitation, i.e. brain, spine, femur, heart, major arteries have equal probability of stop for one shot for any of the calibers 22LR/9mm/45.

  • High probability hit to the non vital areas have equal probability per hit and have equal effectivity per hit for any of the calibers 22LR/9mm/45.

  • Outside of the high effectivity low probability hits to vital areas, incapacitation only happens by blood loss, but each hit has for 22LR/9mm/45 cal equal practical effectivity, and probability of reducing time to incapacitation is based on number of hits more than caliber.
L. M. Sturdivan
U.S. Army Chemical Systems Laboratory, Aberdeen Proving Ground, MD, October 1981