Air guns generate a large number of shot injuries, while pellets can produce life-threatening or lethal injuries by penetrating deep tissue. The assessment of air gun injuries include determining the direction and the distance of the shot, the type of arm, and the penetration capability of the pellet. Answering these questions can be challenging since air gun injuries have received less attention in scientific studies. This study aimed to determine skin and soft-tissue penetration capabilities and wound characteristics of air guns at different impact energies. Test shots were conducted on porcine tissue and ballistic gel with 0.177 caliber air guns from different shooting distances between impact energies of 3.28 and 15.71 J (111 m/s to 243.5 m/s). Entrance wound appearance, size, and penetration depth were compared. The penetration capabilities of the pellet with different impact energies are assessed and discussed. No difference was found in the entrance wound shape and appearance between shots from different distances and impact energy. The results indicate that 0.177 caliber air guns above 7.5 J of muzzle energy can easily penetrate deep into soft tissue, thus able to cause severe, life-threatening injuries. An air gun with a muzzle energy below 7.5 J muzzle energy can still cause severe injury up to 20–30 m as the projectile has enough energy to create several centimeter-deep penetrations.

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.