SHOTGUN PELLETS RICOCHETING OFF STANDARD FLOOR TILES; A FORENSIC-BASED EMPIRICAL STUDY

Introduction

Compared to handguns and rifle bullets, experimental studies that explain the ricochet behaviour and surface evidence when shotgun pellet ricochet are observed to be far fewer. This empirical study examined the ricochet behaviour and impact evidence when shotgun pellets ricochet off standard floor tiles. The combination of firearm and target type selected for this study is believed to be likely reported during urban shooting incidents; therefore, the findings from the study are expected to have a greater practical significance to refer to during future real-time shooting investigations.

Methods

A firmly mounted 12 gauge shotgun (12-bore break-action single-barrel) on a stable steel platform was used to fire at floor tile samples (fixed on concrete using standard masonry practise) held at different angles to the axis of the gun’s bore. SIMAD 12 gauge buckshot ammunition (model 11/0)/ 9 x spherical pellets) were used for the experiment. A Doppler radar (LabRadar v.1.3 with ± 0.1% accuracy) was used to measure the velocity of the shots. Cardboard screens were placed 120 cm away from the centre of the tile surfaces to capture the impacts of ricocheting pellets.

Data collection started by placing a target sample at 10 degrees to the barrel axis. 10 shots repeated at each angle, and the target tray’s angle increased at 10-degree intervals. The impact evidence on tile surfaces and cardboard screens was noted and photographed. The widths and lengths of all ricochet marks produced on the surfaces by impacting pellets and shot spread on tile surfaces and screens were measured and recorded at different impact angles using a vernier calliper.

Results

1. A novel and statistically significant relationship between the lengths and widths of individual ricochet marks and the shot impact angles is demonstrated, offering useful forensic application.

2. Relationships with high statistical significance were also reported between the shot spreads on the tile surfaces and the post-ricocheting pellet spread on cardboard witness screens, with shot impact angles.

3. Impact marks similar to the ‘Pinch Point’ reported in previous studies with painted sheet metal and ceramic tiles were observed at 30 degrees. This feature has not been reported with shotgun pellets in the existing literature, so is a significant highlight. The appearance of these features at 30 degrees onwards highlights a significant forensic value for shooting reconstructions. A feature similar to the ‘Nucleus’ ricochet mark was reported with all pellet ricochets at 40 degrees, presenting an angle-specific characteristic for these shotgun pellets on tile surfaces.

Conclusion

Ricochet behaviour and impact evidence, when shotgun pellets ricochet off standard floor tiles, were explored. The relationships presented on pre- and post-ricocheting pellet spread and findings related to ricochet marks in this study have not been previously reported. It provided an empirical-data-based model of pre and post-ricocheting behaviour of shotgun pellets ricocheting off hard flat tile surfaces at a close distance. This study`s findings have a great potential for use in forensic shooting reconstruction processes.