You understand some of the essential elements at play. As you noted, blood loss. Air embolism as well, along with pneumothorax (and sometimes hemothorax), airway compromise, and infection. If you’re in EMS or have been trained on TC3 those are what you’ve been trained to treat in order to save lives. That is what kills, not “energy”; simply big holes in and big holes out that intersect with important organs and blood vessels along the way — generally energy beyond what is necessary to push a projectile through a body is going to be uselessly zinging off into the wild blue yonder. Hydrostatic shock is largely a myth, and will be until we’ve got man-portable railguns firing hypersonic or high-hypersonic projectiles.
Self defense ammunition must, by definition, quickly and reliably stop an IMMEDIATE threat to your life or the lives of others. However, there’s a tradeoff we have to deal with here, as you noted. The most lethal ammunition we could use, the same ammunition we would choose to hunt large game with due to it’s ability to quickly, reliably, and humanely drop an animal, is simply NOT suitable for self-defense; despite its ability to quickly stop a would-be-murderer.
I would choose to hunt large North American animals with jacketed soft-points, or something like hard-cast lead in a semi-wadcutter or Keith-style if I were using a lever-action. Due to the ability of those particular projectile designs to reliably penetrate completely through an animal while retaining mass, and creating large entry and exit wounds to facilitate rapid blood loss and air embolism, such projectiles make ideal choices for quickly, reliably, and humanely harvesting large game. However such projectiles are not well-suited to self-defense despite their extreme lethality.
By definition a self-defense situation is a situation where I am required to immediately take a shot in order to save my life or the lives of others; by definition I will NOT be able to wait for the perfect shot angle some other day, by definition I will likely NOT be afforded the luxury of choosing to hold my fire until I have a safe backstop and a clear range, by definition I will be reacting to an assailant and likely doing so under unfavorable circumstances. There may be innocent bystanders just a sheet-rock wall away.
Whenever possible one would wish to avoid such nasty situations, and not just because no sane, decent human being wishes to take another person’s life. Whenever and wherever possible people that understand the realities of self-defense try to do everything in their power to avoid situations where self-defense would be necessary — by avoidance, by deterrence, by deescalation, whenever possible. For those reasons I’d like to see public policy and social institutions in place that deter, discourage and reduce crime, as well as incapacitate criminals, but sadly liberals appear to prefer policies that enable, encourage, embolden, facilitate and even create criminals.
But when such situations cannot be avoided, and immediate action must be taken in order to save lives, the most rational trade-off between reliably stopping an assailant and not sending lethal projectiles sailing into the night is to choose a modern bonded jacketed hollowpoint. Typically these are designed to reliably penetrate deep enough to reach vital organs, causing enough damage to physically incapacitate someone trying to do severe harm to yourself or others, while reducing (only reducing) the chance that the projectiles will over-penetrate and pose a threat to bystanders. A projectile that cannot reliably penetrate deep enough to reach vital organs is unlikely to physically incapacitate an assailant, and a projectile that penetrates completely through an assailant is a threat others — hence the reason law enforcement agencies have adopted standards and testing procedures to guarantee that ammunition achieves those parameters.
Look at the type of ammunition your local police departments issue, chances are it’s going to be something along the lines of Ranger, Gold Dot, Golden Saber, the like; all modern bonded jacketed hollowpoints from reputable, established manufacturers that extensively test their offerings and have their ammunition tested by the DOJ or other agencies prior to wide-scale adoption by law enforcement agencies.
Not birdshot, not incendiaries, not foil-wrapped compressed-lead powder, not flechettes, and certainly not a miniature copper fork. Seriously, it may sound boring, but Winchester, Remington, and Federal are in business because they make cartridges that work for their intended purposes. If something really, truly, was a better mousetrap, you’d quickly see it being used by the people whose lives depend upon it and you’d see it or a knock-off of it offered by all the major manufacturers. It’s important to avoid useless gimmicks and the companies that peddle them - they’ll probably sound neater than hell, that’s how the unscrupulous companies selling them expect to make money, but there’s no place for showmanship and snakeoil in life-or-death decisions.
That video I posted earlier shows the RIP ammo performing about as well as two shots from a .22LR, effectively downgrading a capable 9mm pistol into the equivalent of a .22 Derringer. To all the freepers out there, if you are choosing ammunition for a self-defense weapon that you’re going to trust your life to, please pick more effective ammunition than the little-copper-fork.