Per Anthony J. Pinizzotto, Harry A kern and Edward F. Davis in FBI law enforcement bulletin October 2004, with the exceptions of hits to the brain or upper spinal cord, the concept of reliable and reproducible immediate incapacitation of the human target by gunshot wounds to the torso a.k.a one shot drop is a myth. However, many shooting scenes in majority of films and television programs show unrealistic reactions and expectations regarding ballistic effects.
Physiologically, a determined adversary can be stopped reliably and immediately only by a shot that disrupts the brain or upper spinal cord. Failing to hit the center nervous system, massive bleeding from holes in the heart, or major blood vessels of the torso causing
circulatory collapse is the only way to force incapacitation upon an adversary, and this takes time. For example, there is sufficient oxygen within the brain to support full, voluntary action for 10 to 15 seconds after the heart has been destroyed.
Realistic and regular law enforcement training must counterbalance and mentally and emotionally override the fallacy of the one-shot drop still promoted by some media. Short
of disrupting the brain or severing the upper spinal column, immediate incapacitation does not occur. Therefore, the threat remains to the officer.
Yet, implicit in the media presentations of law enforcement encounters is the belief that with the “proper handgun” and the “proper ammunition,” officers will inflict immediate incapacitation if they shoot offenders anywhere in the torso. Varied and multiple real-life law enforcement experiences contradict this false and dangerous belief. Social science
discloses that if people expect to see something, they well may see it.
Per J. Scott Denton et.al. in 2006,
Generally, 3 factors determine the severity of a gunshot injury: the amount of kinetic energy transferred by the bullet to the surrounding tissues, the internal organs and
structures damaged by the bullet, and the bullet’s final disposition. Obviously, the anatomic location of the wound is critical—a gunshot wound to the central nervous system, even one of low velocity, can be more life threatening than a high-velocity wound through the arm. Involvement of vital structures such as the heart, aorta, lung, liver, spleen,
and kidneys can quickly lead to hemorrhage, hypoxia, and death.
Per Special Agent Urey W. Patrick who belongs to the Firearms training Unit, FBI Academy in 1989,
A bullet simply cannot knock a man down. If it had the energy to do so, then equal energy would be applied against the shooter and he too would be knocked down. This is simple physics, and has been known for hundreds of years. The amount of energy deposited in the body by a bullet is approximately equivalent to being hit with a baseball. Tissue damage is the only physical link to incapacitation within the desired time frame, i.e., instantaneously.
The human target can be reliably incapacitated only by disrupting or destroying the brain or upper spinal cord. Absent that, incapacitation is subject to a host of variables, the most important of which are beyond the control of the shooter. Incapacitation becomes an eventual event, not necessarily an immediate one. If the psychological factors which can contribute to incapacitation are present, even a minor wound can be immediately incapacitating. If they are not present, incapacitation can be significantly delayed even with major, unsurvivable wounds.
Further, it appears that many people are predisposed to fall down when shot. This phenomenon is independent of caliber, bullet, or hit location, and is beyond the control of the shooter. It can only be proven in the act, not predicted. It requires only two factors to be effected: a shot and cognition of being shot by the target. Lacking either one, people are not at all predisposed to fall down and don't. Given this predisposition, the choice of caliber and bullet is essentially irrelevant. People largely fall down when shot, and the apparent predisposition to do so exists with equal force among the good guys as among the bad. The causative factors are most likely psychological in origin.
Physiologically, no caliber or bullet is certain to incapacitate any individual unless the brain is hit. Psychologically, some individuals can be incapacitated by minor or small caliber wounds. Those individuals who are stimulated by fear, adrenaline, drugs, alcohol, and/or sheer will and survival determination may not be incapacitated even if mortally wounded.
The will to survive and to fight despite horrific damage to the body is commonplace on the battlefield, and on the street. Barring a hit to the brain, the only way to force incapacitation is to cause sufficient blood loss that the subject can no longer function, and that takes time. Even if the heart is instantly destroyed, there is sufficient oxygen in the brain to support full and complete voluntary action for 10-15 seconds.