The effect of helmet materials and simulated bone and tissue layers on bullet behaviour in a gelatine model of overmatch penetrating head injury

Abstract

The aim of this work was to simulate an overmatch ballistic event against a head wearing a helmet. The experiments were designed to understand how layers of bone (or synthetic bone), synthetic skin and currently used helmet materials influence the behaviour of full metal jacket mild steel core (FMJ MSC) 7.62 × 39 mm bullets, impacting on targets with a mean velocity of 650 m/s. Bullet behaviour within 10% (by mass) gelatine blocks was assessed by measurements made of the temporary cavity within the blocks using high-speed video and of the permanent cavity by dissecting blocks post firing. While ANOVA did not find significant difference at the 0.05 level in the mean values of most of the measurements, there was a significant difference in neck length within the gelatine blocks. The addition of material layers did produce greater variability in the temporary cavity measurements under some of the conditions. One of the synthetic bone polymers with a synthetic skin layer produced similar results within the gelatine blocks to the horse scapulae (with residual tissue) and may be suitable for future ballistic experiments.

Forensic reconstruction of two military combat related shooting incidents using an anatomically correct synthetic skull with a surrogate skin/soft tissue layer

“…Bullet behaviour within the models could be inferred from the permanent cavity in the gelatine brain, the exit fracture patterns and the resting place of the bullet within the helmet structure, and the flash X-ray images were helpful to confirm this. While the mean neck length in the gelatine brains of models 1-3 (see 'Results') was similar to that of gelatine blocks in our earlier work [16] with intermediate targets of sheets of the same helmet material, synthetic skin and synthetic bone, there was greater variability in the blocks. Further work is needed to understand how comparable the models are.…”

“…The bullet path in the gelatine brains of models 4 and 6 was too small due to the tangential strikes to make meaningful measurements. The mean neck length in gelatine blocks with sheets of the same synthetic materials as intermediate targets described in [16] was 56 mm (SD 27 mm), but the SD was much greater.…”

“…In order to allow comparison with our previous work [9,10,16], casualties were identified where 7.62-mm bullets were confirmed responsible for the injuries (this included 7.62 × 39, 7.62 × 51 and 7.62 × 54R mm). Seven casualties were confirmed as such.…”

Ballistic research techniques: visualizing gunshot wounding patterns

“…Damage caused to a target by the impact of a projectile in research can be measured in a number of ways, for example, depth of penetration (DoP), kinetic energy (KE) transfer, or calculation of area or volume of damage [1][2][3][4][5][6][7][8][9][10][11][12]. One of the challenges associated with gathering such data is to optimise the method(s) used for the target material under study.…”

“…With synthetic models such as gelatine, the relative transparency allows for visual analysis of gunshot wounding (GSW) using techniques such as high speed video (HSV) to capture the effect of the projectile on the target in real time [6,10,12,14]. With respect to the study of GSW in cadaveric or live tissue, one of the difficulties in the analysis of wounding patterns is the opacity of the surrogate.…”