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Below article is good to look at I think as we talk about the subject re: stopping power. If we talk stopping power we always compare the most popular caliber i.e. 9mm and .45 caliber in the fast and slow school of thoughts.
Stopping power, also called terminal ballistics, is how bullets kill or incapacitate people and animals. The context may be self-defense, military, or hunting. This article assumes the target is human, but it applies also to animals.
Most theories about stopping power rely on impressive-sounding yet meaningless terminology--such as "energy transfer" and "hydrostatic shock"--to hide the fact that they have minimal basis in reality. Such strange, elaborate theories have only formed around firearms. People do not often claim that a particular knife or club has an "80% chance of a one-hit stop," or "transfers 400 foot-pounds of energy to the target." Popular entertainment portrays guns; if you're shot, you fall over dead. People infer that guns must be mystical weapons, capable of doing things no other weapon can, and so may require an equally mystical system for explaining the effects.
Performance
The 9 mm Luger cartridge combines a flat trajectory with moderate recoil, and fair stopping power. Its main advantages lie in its small size and low use of resources for manufacturing. Its main disadvantages are its tendency to overpenetrate and poor permanent cavitation (hole size), when nonexpanding bullets are used.
Because it is inexpensive, easy to manufacture and effective enough for most uses, it has become the most used pistol cartridge in the world.
For police use, it is mainly used with higher speed overpressure (+P) expanding bullets to increase both permanent and temporary cavitation, and to reduce overpenetration.
Energy, generally and qualitatively speaking, is the property (or the quantity of the property) of changing the state of a system or doing work.
It should be noted that the impact to the target can be no greater than the impact of the recoil, due to the law of conservation of momentum. However, the smaller size of the bullet, compared to the gun-and-shooter system, allows significantly higher energy to be imparted to the bullet than to the shooter. This is what gives guns their lethal effect. See physics of firearms for a more detailed discussion.
What people do when shot
What a person does when shot depends on a very large number of factors. A person can be incapacitated by either the psychological or the physiological effects.
Psychological effects
Emotional shock, terror, and surprise can cause a person to faint dead away when shot. This is the likely reason for most "one-shot stops," and not any intrinsic quality of any one bullet.
The realization that one has been shot, or at least shot at, is also often enough to cause a person to give up or flee.
Pain is another psychological factor. Having holes put in your body hurts quite a bit, after all, and can quite possibly be enough to dissuade a person from doing anything but screaming.
If a person is sufficiently enraged, determined, drugged-up, or just plain mean, however, they can simply shrug off any psychological effects of being shot, so they should not be counted on to stop an attacker.
Physiological effects
The only way to physiologically stop a person is to damage or distrupt their central nervous system (CNS) to the point that they fall unconscious or die.
Bullets can achieve this directly or indirectly. If a bullet causes sufficient damage to the brain (particularly the cerebellum or brain stem) or cervical spinal cord, the CNS damage is direct and nearly instant. These targets are very small, well-protected, and mobile, however, making them difficult to hit even under optimal circumstances; it is not unheard of for a bullet to skim along the skull, just under the skin, or even be stopped outright in the case of very weak calibers. Similarly, a bullet which passes through the neck or upper chest might not have the velocity to break the spine and damage the spinal cord itself.
Indirectly, bullets can damage the CNS by way of bleeding. This is accomplished by putting a large enough hole through a vital enough blood vessel or blood-bearing organ. If blood-flow is completely cut off from the brain, a human still has enough oxygenated blood in their brain for 10 seconds of willful action. Considering that a person's higher brain functions will usually shut down in a life-or-death situation, this figure might actually be a bit low.
Major blood vessels include the superior aorta, inferior aorta, vena cava, brachial arteries, femoral arteries, carotid arteries, and jugular veins.
Major blood-bearing organs include the heart, kidneys, and liver.
Unless a bullet strikes and damages a CNS structure, there is absolutely no physiological reason for a person to be instantly incapacitated, and unless the bullet crushes a large enough hole in a major blood vessel or a major blood-bearing organ, there is no physiological reason for them to be incapacitated at all.
Below article is good to look at I think as we talk about the subject re: stopping power. If we talk stopping power we always compare the most popular caliber i.e. 9mm and .45 caliber in the fast and slow school of thoughts.
Stopping power, also called terminal ballistics, is how bullets kill or incapacitate people and animals. The context may be self-defense, military, or hunting. This article assumes the target is human, but it applies also to animals.
Most theories about stopping power rely on impressive-sounding yet meaningless terminology--such as "energy transfer" and "hydrostatic shock"--to hide the fact that they have minimal basis in reality. Such strange, elaborate theories have only formed around firearms. People do not often claim that a particular knife or club has an "80% chance of a one-hit stop," or "transfers 400 foot-pounds of energy to the target." Popular entertainment portrays guns; if you're shot, you fall over dead. People infer that guns must be mystical weapons, capable of doing things no other weapon can, and so may require an equally mystical system for explaining the effects.
Performance
The 9 mm Luger cartridge combines a flat trajectory with moderate recoil, and fair stopping power. Its main advantages lie in its small size and low use of resources for manufacturing. Its main disadvantages are its tendency to overpenetrate and poor permanent cavitation (hole size), when nonexpanding bullets are used.
Because it is inexpensive, easy to manufacture and effective enough for most uses, it has become the most used pistol cartridge in the world.
For police use, it is mainly used with higher speed overpressure (+P) expanding bullets to increase both permanent and temporary cavitation, and to reduce overpenetration.
Energy, generally and qualitatively speaking, is the property (or the quantity of the property) of changing the state of a system or doing work.
It should be noted that the impact to the target can be no greater than the impact of the recoil, due to the law of conservation of momentum. However, the smaller size of the bullet, compared to the gun-and-shooter system, allows significantly higher energy to be imparted to the bullet than to the shooter. This is what gives guns their lethal effect. See physics of firearms for a more detailed discussion.
What people do when shot
What a person does when shot depends on a very large number of factors. A person can be incapacitated by either the psychological or the physiological effects.
Psychological effects
Emotional shock, terror, and surprise can cause a person to faint dead away when shot. This is the likely reason for most "one-shot stops," and not any intrinsic quality of any one bullet.
The realization that one has been shot, or at least shot at, is also often enough to cause a person to give up or flee.
Pain is another psychological factor. Having holes put in your body hurts quite a bit, after all, and can quite possibly be enough to dissuade a person from doing anything but screaming.
If a person is sufficiently enraged, determined, drugged-up, or just plain mean, however, they can simply shrug off any psychological effects of being shot, so they should not be counted on to stop an attacker.
Physiological effects
The only way to physiologically stop a person is to damage or distrupt their central nervous system (CNS) to the point that they fall unconscious or die.
Bullets can achieve this directly or indirectly. If a bullet causes sufficient damage to the brain (particularly the cerebellum or brain stem) or cervical spinal cord, the CNS damage is direct and nearly instant. These targets are very small, well-protected, and mobile, however, making them difficult to hit even under optimal circumstances; it is not unheard of for a bullet to skim along the skull, just under the skin, or even be stopped outright in the case of very weak calibers. Similarly, a bullet which passes through the neck or upper chest might not have the velocity to break the spine and damage the spinal cord itself.
Indirectly, bullets can damage the CNS by way of bleeding. This is accomplished by putting a large enough hole through a vital enough blood vessel or blood-bearing organ. If blood-flow is completely cut off from the brain, a human still has enough oxygenated blood in their brain for 10 seconds of willful action. Considering that a person's higher brain functions will usually shut down in a life-or-death situation, this figure might actually be a bit low.
Major blood vessels include the superior aorta, inferior aorta, vena cava, brachial arteries, femoral arteries, carotid arteries, and jugular veins.
Major blood-bearing organs include the heart, kidneys, and liver.
Unless a bullet strikes and damages a CNS structure, there is absolutely no physiological reason for a person to be instantly incapacitated, and unless the bullet crushes a large enough hole in a major blood vessel or a major blood-bearing organ, there is no physiological reason for them to be incapacitated at all.
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