Bullet Retarding Forces in Ballistic Gelatin by Analysis of High Speed Video

TL;DR

This study introduces a high-speed video analysis method to measure retarding forces of bullets in ballistic gelatin, revealing differences in wounding potential among various 9mm NATO bullets and aiding in rapid incapacitation predictions.

Contribution

The paper presents a novel frame-by-frame high-speed video technique to quantify retarding forces and energy transfer during bullet penetration in tissue simulants, enhancing wound ballistics analysis.

Findings

Different 9mm bullets show wide variation in wounding potential.

The technique accurately predicts relative effectiveness of bullets.

Energy transfer in initial penetration correlates with incapacitation likelihood.

Abstract

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.