DiMaio explains that when a full metal jacketed 5.56/.223 round contacts human tissue it will travel along a circular path while beginning to yaw or turn sideways. This turning effect will become significant at 12 cm (approximately 4.7 inches).
At the point of maximum yaw, the bullet will be turned at a 90-degree angle as it moves forward in the body.
If the bullet remains intact, it will yaw to 180 degrees and continue to travel base first until it comes to rest.
Handgun rounds do not yaw while traveling through human tissue.
This turning or yaw effect releases tremendous kinetic energy into the tissue surrounding the permanent cavity created by direct bullet contact with human tissue. Not only is the permanent cavity larger due to the sideways path of the bullet, thereby destroying more tissue through direct bullet contact, but the surrounding tissue, i.e., tissue not directly touched by the bullet, is severely impacted as well. This surrounding tissue is called the temporary wound cavity.
DiMaio reports that this temporary cavity will have a diameter from 11 to 12.5 times the diameter of the bullet itself.
Damage to the tissue in the temporary cavity will include “severe…compression, stretching, and shearing of the displaced tissue. Injuries to blood vessels, nerves, or organs not struck by the bullet, and at a distance from the [bullet] path can occur.”