A loss of blood pressure can kill, but not as fast as a stoppage of blood flow to the brain. When oxygenated blood does not reach the brain, the heart and lungs can't function. Also, a shot to the brain can kill faster than a loss of blood pressure. A shot to the neck or spine that breaks the cervical nerves, specially the C6 and C7, can also kill pretty fast without much blood pressure loss.
That said, a big hole only makes a difference if it is though any body organ that carries lots of blood, or the heart itself. For example, the arteries by the heart, neck, and upper thighs on humans (near the groin) carry a lot of blood under pressure. There aren't very large blood vessels in the lungs, but a disruption to the lungs function such as the shock from a shot, as well as bleeding in the lungs, can kill, but at a slower rate depending on the amount of shock. Then take the heart beat of a brown bear at 40 beats per minute, an animal that can get to you within a few seconds, even if the heart has a big hole though it.
My experiences with the 225-grain Barnes 3-Shock bullets have been as positive as the NOS Partition, the 250-grain A-Frame, and the 230-grain Lubalox-coated FS, at least on moose. While a complete loss of blood pressure eventually kills, it does no kill as fast as when the CNS is damaged as mentioned above. But since I am not an expert on such things, please take my words with a grain of salt.
Ray, FWIW I have a certain degree of expertise in this area, and I agree with your assessment
for the most part. As Dr. Martin Fackler posited, there are only TWO reliable means of incapacitation by gunshot wound: trauma to the CNS, and rapid blood loss that deprives the CNS of oxygen. In other words, you have to stop the CNS, either directly or indirectly.
CNS hits incapacitate immediately. Blood loss incapacitation is extremely variable and unpredictable. In my professional experience as a trauma physician, I have observed this phenomenon at first hand, but also have access to the breadth and depth of the trauma medicine literature, which basically says the same thing. People and animals can accomplish amazing and heroic feats of strength, endurance, and tenacity in the short term despite catastrophic blood volume loss. Others keel over and die slowly with a less dramatic wound. You simply can't predict the speed with which a fatal non-CNS GSW will cause the recipient to cease purposeful action.
Whether a GSW produces only one external wound (entrance) or two (entrance + exit) is irrelevant to lethality or speed of exsanguination. The only advantage to having a second hole in the skin is that twice as much blood will spill onto the ground for tracking. The chest cavity can accommodate the entire blood volume of an animal or person, it doesn't have to escape from the chest to result in a loss of blood pressure. To argue that a bullet that does not produce an exit wound has "failed" is beyond ridiculous.
As for holes in the heart, I have to disagree with you... the size of the hole is far less important than the location of the hole; and, I strongly suspect, the time in the systole-diastole cycle of the heart when the bullet hits is also probably an important factor that needs to be studied in greater detail. The reality is that not all "heart shots" are equal, and in fact, there is a high degree of variability of effect in heart shots. The heart is a large, complex, and very tough organ. I'm aware of a number of cases of people who've taken a bullet through the heart who have survived long enough to have lifesaving surgery, and went on to live productive lives thereafter. Quadrupeds are no less subject to the vagaries of GSW's to the heart, so it's no surprise that some Dangerous Game have rampaged through an entire hunting party with the hearts "shot out", while others have rolled over and died very quickly.
No two GSW's are the same. The number of variables involved in the mechanics of the GSW is enormous, and then if you add in physiological/dynamic variables, the possible outcomes expand exponentially. Claiming that one particular type of bullet is a guaranteed "fail"--or a guaranteed "win"--based on one hunter's limited opportunities for observation, is an exercise in oversimplification that fails to take into account the complexity of the problem.
