Resident Manual of Trauma to the Face, Head and Neck

Table 2.1. Caliber, Muzzle Velocity, and Energy of Commonly Used Weapons Caliber Muzzle Velocity Energy (ft-lb) .32 745 140 .357 1410 540 .38 855 255 .44 1470 1150 .45 1850 390 9 mm 935 345 .243 Winchester 3500 1725 M16 (.223 cal or 5.56 mm) 3650 1185 7.62 Nato rounds 2850 1535 AK47 3770 1735 ft-lb = foot-pounds; mm = millimeter. b. Projectile Design i. Projectile Characteristics Influencing Energy Transfer All projectiles passing through soft tissue create a permanent cavity, or tract, that is generally apparent on initial examination. If a bullet destabilizes upon contact with tissue, it deforms, yaws, tumbles, or fragments, causing greater tissue destruction (Figure 2.1). Thus, exit wounds tend to be larger than entry wounds. Tissue damage is propor- tional to the energy transferred to the tissues. The energy transfer is influenced by four projectile characteristics: y y Yaw —The deviation of the projectile in its longitudinal axis. y y Tumble —The forward rotation around the center of mass.

y y Deformation of the projectile. y y Fragmentation of the projectile.

Figure 2.1 Four characteristics of projectile missiles.

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