Features of the ejection and topography of the distribution of metal particles of a destroyed projectile after overcoming an obstacle made of triplex glass of a car

BACKGROUND: The article describes experimental studies aimed at studying the features of post-retrograde gunshot trauma using the latest modern methods of forensic medical research.

AIMS: The aim of the work was to study the nature of the distribution of metal particles of a destroyed firearm projectile after passing through an obstacle ― triplex glass.

MATERIAL AND METHODS: As a barrier, car windshield triplex windows are used, located at an angle of 60° to the aiming line. The shots were fired from the Saiga-MK carbine with 5.45×39 BPZ FMJ cartridges. During the experiments, shots were fired from a distance of 10 m (a total of 30 shots were fired). White cotton fabric (calico) with dimensions of 100×150 cm, fixed on a chipboard, was used as targets. The distance between the target and the barrier was 100 cm. The targets were studied using a scanning electron microscope Hitachi FlexSem 1000 II and an energy-dispersive X-ray spectrometer Bruker Quantax 80. In the course of the experiment, high-speed video shooting was carried out with a Sony RX0 video camera with a frequency of 1000 fps.

RESULTS: A frame-by-frame study of the obtained video recordings showed that the deviation of the flight of the projectile fragments from the original trajectory was up to 10º side of the normal to the back surface of the glass. The fragments of the projectile, having overcome the barrier, moved in stages, in 3 phases: overcoming the barrier, ejecting fragments in the form of a cone, breaking through the target and retrograde movement of the fragments of the barrier. The scanning electron microscope and energy dispersive spectroscopy studies showed that the topography and morphology of the distribution of metals on the target surface correspond to the data of the analysis of the movement of parts of a firearm during high-speed video shooting. The metal alloy found on the target contained the following elements: plumbum (Pb), cuprum (Cu), antimony (Sb), and kalium (K).

CONCLUSION: When conducting an experimental study, it was found that various types of particles that were destroyed during the passage of the barrier, a firearm projectile, are registered on the surface of the target. The nature of the particle distribution and their morphology are very specific, and most likely a qualitative assessment of the projectile particles on the target will allow us to determine the distance of the shot beyond the barrier.