Military munitions and firearms produce injuries not commonly seen in civilian trauma. Weapon types can be roughly divided into two major subtypes: small arms fire and explosive munitions. Small arms fire is typically from hand guns and assault rifles.1

When a small arms projectile hits tissue, it produces two types of injuries: a permanent cavity and a temporary cavity. The permanent cavity is the tissue destroyed by the actual pathway of the projectile. Military rounds are designed to turn, or yaw, upon contacting tissue. As the bullet turns, the permanent cavity size increases. This is evidenced by small entry wounds and large exit wounds. A second, temporary cavity occurs from a pressure wave created by the high-velocity round. Elastic, and inelastic tissue, is put under stress which manifests as delayed necrosis and is one of the reasons we do not advocate for wound closure following the initial debridement. The degree of damage is proportional to a projectile’s kinetic energy and more specifically its velocity (Kinetic Energy = ½ (Mass) x Velocity). Particles distributed by blast explosions also create permanent and temporary cavities.