Good, thoughtful post.
I suspect that there are small, not necessarily high speed rounds, that are truly awful in the amount of damage that they do. Research goes on in many areas in this regard.
There is a very limited range of recoil available to ammo manufacturers in pistols. They have to be within this range in order to market their wares. Any round that exceeds it by a healthy margin will fail in the market because it is unpleasant to shoot and may be inaccurate to boot.
The maximization of damage from a small round is exactly the objectives that have been met rather well by ammo manufacturers with the Barnes bullets and others (I am not at all sure who is doing this as I am a cast boolit guy and I don’t care).
You mention hard cast bullets and reloaders. Most commercial bullets that are lead cast are usually BHN 24 (exand in the barrel at 34,000 Psi) which for you civilians is extremely hard. They tend to be undersized as well in order to fit many different guns and the result is leading, particularly at the forcing cone of a pistol and the first inch or so of the barrel because they fail to expand to seal the bore and rifling due to their hardness.
The reason they are cast so hard has to do with shipping. Softer bullets will become marked and dented if they are shipped, stored (average storage time is a little bit more than one year for most ammo) and moved very much and customers don’t like that.
I belong to several casting and reloading forums and one of the public services we provide is to disabuse new casters of their belief that hard cast bullets are better. They are inherently less accurate and will leave large quantities of lead in the gun. Most guns shoot fine with bullets that are of BHN of 10 (14,000 psi) to 14 (20,000 psi) but their are some pistols, particulary the higher pressure guns such as .357 mag and the .50 AE that are shot at BHN 18 (25,000 psi), but that is about the practical limit.
I will stop on this point as it suddenly becomes rather complicated but the action of hard cast bullets is not at all what you wish in a defensive scenario. They may not expand or they may shatter and fragment, which is less effective than simply mushrooming.
I agree that the aregument that loads being to hot for defense use is moot. If that were the case 12 gauges and .357 mags would be outlawed.
Very well considered and written. Thanks for the info on defense against human attackers. I didn’t know about the 24 Brinnell bullets! That’s really hard! Softer lead makes sense, as most human attackers won’t present a deep target (e.g., torso from front to rear) while attacking.
If you haven’t already seen it, here’s something else that you might enjoy. Mostly about revolver tech. more in regards to hunting, though.
Gun Notes: The .45 Colt - Dissolving the Myth, Discovering the Legend
by John Linebaugh
http://www.customsixguns.com/writings/dissolving_the_myth.htm