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.