Intermediate Cartridge Wounding Profiles

[Cosmoline]

I think there is some magic velocity where there is enough energy imparted to the target rapidly enough to make the temporary cavity into a permanent wound.

You're onto something there. I've seen historical references to a "magic" velocity of around 2,100 fps from a rifle round at impact. The "explosive" wounds from rounds of this velocity were first noticed with the advent of smokeless powder in the Spanish-American war from the 7x57 rifles. So it's not just imagination. But it's a fuzzy number, since we're dealing not just with the bullet's physics but the resistance of internal tissues around the particular bullet hole. If the hole goes through fatty tissues, even a very large cavity means little. If it's right next to the heart then it can kill.

 

[Skribs]

I've seen references to a velocity of around 2,100 fps from a rifle round at impact. These "explosive" wounds were first noticed with the advent of smokeless powder in the Spanish-American war from the 7x57 rifles. It's basically the velocity that's just beyond the reach of ordinary black powder firearms.

But it's a fuzzy number, since we're dealing not just with the bullet's physics but the resistance of internal tissues.

I've heard differing numbers as well. One poster on THR (can't remember who atm) had a theory that the caliber of the meplat (expanded or not) would have an effect on the velocity needed to achieve an increase in permanent wound channel. Something along the lines of if you need 2" of cavitation trauma to cause permanent damage, then the cavity needs to stretch 2" - meplat in order to break that threshold. Not sure if that's true or not (it might need to be 2" from the edge of the crush trauma, for example) but it's an interesting take.

That's what I'm referring to by the "balloon" effect, is that the rifle creates a moderate crush cavity (actually probably a smaller crush cavity than a 9mm JHP), but it does its damage through cavitation trauma. In my OP, I was wondering if the bullet just zips through (as multiple sources linked say can happen with a long neck length) then the 9mm will crush more tissue in its path, and actually affect the target more, especially because the long neck length of the wound tract is due to the bullet travelling straight instead of yawing.

So while I can trust the 9mm round to make a 0.6" circular hole through the target, the .223 round may make a 0.223" hole at the neck, a 3" hole during the yaw/fragmentation, or a 0.223x1" hole at the tail-end of the penetration. So at one point the .223 will make a significantly larger hole (thus leading to the target bleeding out faster, which doesn't necessarily mean it will stop the target in the time needed for SD), but at the other points it will make a smaller hole than the pistol cartridge.

Hunting is a little different than SD, because while a hunter wants to kill quickly, it doesn't seem to be that important that the the deer drop RIGHT THERE. A self defense shooter needs the target to stop ASAP.

 

[HorseSoldier]

Wound channels in gelatin have a limited relationship to actual terminal bullet performance, as has been stated. Unless the temporary cavity is through some critical and non-elastic tissue like the liver it may or may not have much bearing on lethality or incapacitating capability.

The big payoff for a center fire rifle round at defensive shooting ranges in the dramatically greater energy it possesses compared to most pistol rounds. The old energy transfer ballistics theories are overly simplistic to the point of being irrelevant, but a rifle round has enough energy that we're not really worrying about FBI clothing/tissue penetration standards. That energy can translate into additional injury from temporary cavity and things like destroying bone and creating secondary fragments -- but it may not, too.

The other big plus with a long gun versus a pistol is just that at self-defense ranges, what are hard/low percentage shots with a handgun are pretty much chip shots with a shotgun, carbine, or rifle.

 

[Skribs]

The other big plus with a long gun versus a pistol is just that at self-defense ranges, what are hard/low percentage shots with a handgun are pretty much chip shots with a shotgun, carbine, or rifle.

I'm not picking between a rifle and pistol, but an intermediate cartridge vs. a pistol cartridge, both fired from a long gun.