bullets

To understand where the worst place to be shot is, you must first understand a little bit about bullets and the effects they have on the human body.
The study of what bullets do to tissue, bone and organs is called wound ballistics, and this field has come up with some definite conclusions about the destructiveness of projectiles on humans. A bullet is a carrier of force, and its purpose is to transfer that energy within the body.
The injury inflicted by a bullet is directly related to the bullet's kinetic energy. This is a measure of the bullet's weight, velocity and gravitational trajectory. The combination of the three describe how much damage a bullet will cause.
As a bullet enters the body, it causes laceration and crushing wounds. The bullet punctures tissue and bone, crushing or pushing aside anything in its path. When a bullet passes through tissue, it creates a cavity that can be 30 times wider than the path it takes.This cavity closes behind the bullet less than a second after the bullet passes, but the cavitation it causes can damage nearby tissue, organs and bones via shock waves.
The type and amount of injury sustained from a bullet also depends on what a bullet encounters. Soft tissue can carry shock waves more easily than bone, but since bone is dense, it absorbs more force (and damage). Bones also splinter, causing further damage as the fragments travel through the body as projectiles themselves.
A bullet that passes through the body (creating an exit wound) generally will cause less damage than one which stays in the body, because a bullet that stays in the body transfers all of its kinetic energy (and ensures maximum damage to tissue). This is the aim of most modern ballistic design. Jacketed bullets are designed to fragment after impact, dividing their destructive power. Hollow-point and soft bullets are designed to flatten and spread, creating a wider area for their tracks and increasing the damage caused by shock waves and cavitation.