Beyond lead and diabolo – penetration capabilities of non-traditional air gun projectiles

The traditional air gun pellet is either spherical or diabolo type with a head followed by a narrow mid-section and a skirt. But apart from these traditional homogenous pellets, special ammunition is also available for air guns, including lead-free, dart-shaped, plastic-coated, and "explosive" pellets producing flash and loud bang upon impact. The scientific data on the penetration capability and terminal ballistic behavior of these pellets are very limited. The study aimed to determine and compare the ballistic gel and tissue penetration capabilities of different air gun ammunition. Ballistic gel and porcine skin penetration of eleven types of 4.5 mm diameter (.177) air gun pellets, including traditional diablo-type lead pellets, lead-free pellets, plastic-coated pellets, and ammunition with an "explosive" charge, were examined. The ballistic gel penetration depth was measured using a digital caliper. The porcine test targets underwent computer tomography (CT) examination and the traditional autopsy method. Histological analysis was performed of the entrance wound and wound track of "explosive" ammunition. The muzzle velocity ranged from 75.4 to 245.1 m/s, and the muzzle energy ranged from 2.5 to 8.5 J. The maximal gel penetration ranged from 26.0 to 117.8 mm, and the final projectile position ranged from 23.8 to 113.2 mm. Tissue penetration ranged from 8.5 mm to 102.2 mm, and full-thickness tissue penetration was achieved in 35 shots from 79. RESULTS: indicate large variations in muzzle energy in the case of non-traditional pellets, even if the same weapon is used. Penetration depth does not correlate strongly with muzzle speed in the case of non-traditional pellets, as the shape and type of pellet have a significant influence on penetration. Some non-traditional pellets may leave behind their plastic sheath in the tissues, which requires special attention since these are invisible on CT scans. Pellets with an "explosive charge" leave behind a blackish discoloration around the entrance wound and in the wound track, which is visually identifiable and also visualized in CT.