The op hasn't been back, but if we read his post it's clear that he was asking about defensive shooting and not hunting. Drawing from the experience of hunting can help illustrate some things but misses the mark mostly. As the primary objectives, killing the game with one shot vs. stopping an attack, are different.
For non-central nervous system hits incapacitation is largely caused by a quick drop in blood pressure. Hitting the heart does that quickly. For other areas the blood pressure drop will take a bit of time.
Exit wounds seem to be advantageous as it would make two paths for the blood to exit the body. A single wound with the bullet in the target can still make a bit of back pressure to slow bleeding. Bleeding is more difficult to stop if there are two exit paths.
It seems to me that exit wounds were talked about much more in the past and not so much today. Today bullet performance conversations tend to be about bullet expansion and a minimum penetration of 12 inches...ostensibly to get to vital organs and not necessarily to make an exit wound.
Another aspect of this issue is that a bullet leaving the target faster makes for a larger exit wound than one that barely makes it out. I have seen this in pumpkin shoots. Many times a .45 and a .357 will penetrate the same number of pumpkins, but if you look at the exit wounds from the .357 they are noticeably larger.
I've highlighted a few places in the OP's note. makes it easier to comment on them.
On "incapacitation"...that is a particular thing: "
noun. the state of not having the necessary ability, qualification, or strength to perform some specified act or function; incapacity: When the brain lacks sufficient oxygen, cognitive and mental ability declines, followed by physical incapacitation, and then unconsciousness or even death."
It's not just blood loss that can cause incapacitation. Shock (physical shock can have both physical and psychological causes), terror and pain can cause the temporary inability to function physically.
It's true that both entrance and exit wound can cause more external bleeding. But it's often the case that this takes some time for a person to bleed out to the point that they are physically incapable of fighting. When an immediate stop is needed "bleeding out" is not reliable. This is why there is less talk about that these days in general.
In the 1970's a company named Super Vel the first
reliable expanding jacketed hollow point ammo. This was first done for the 357 Magnum with 110 and 115 gr. bullets moving at close to 1400 fps from a 4" barrel. This brought on a revolution in bullet design. That revolution expanded after the 1986 Miami shootout that effected all calibers.
Following that shootout the FBI developed a protocol. They wanted JHP bullets that could penetrate certain barriers (auto glass, drywall, heavy clothing, sheet metal, etc.) and after that expand and penetrate 12" to 16". This allowed the bullet to hit critical organs, from various angles that a bullet might hit a body at and continue. The expansion also limited penetration. The expansion of the bullets created more damage to tissue. The issue was not to create two holes, though that obviously continues to happen, but to cause more trauma
, rapidly.
Bleeding out, as an objective of bullet performance, takes too long in and of itself. Bullet expansion does create a larger hole when leaving the body, obviously. But the point is to create more damage right now that can create an immediate stop.
Yes, increased velocity can, with the right bullet, create more damage.
