If we’re talking about personal defense against humans (not critters), I think the 9mm is adequate in most cases and here’s my reasoning .... which isn't necessarily scientific.
I’ve found that you can pigeonhole most people’s response to the defensive use of a firearm (good guys & bad guys alike) into three general categories;
Folks in Group #1 will terminate their participation in the conflict when the mere presence of a gun manifests itself. This is far and away the most frequent scenario when it comes to personal conflict. This happens all the time and few people (outside of the players involved) are ever aware it took place. No shots are fired so pretty much ANY gun/cartridge will do.
Folks in Group #2 pretty much lose all interest in continuing the fight when either, (a) ANY shots are fired or; (b) they suffer ANY meaningful hit in pretty much ANY part of their body. Again, pretty much ANY gun/cartridge will do.
Folks in Group #3 however, aren’t the least bit impressed by the presence of a gun or even being shot - they must be STOPPED by either a disruption of their CNS or a loss of blood pressure.
For most people in most circumstances, that is best accomplished with a gun/cartridge combination that allows the user to achieve multiple hits while making some reasonable allowance for multiple misses.
I happen to think that's a good role for a properly loaded hi-cap 9mm …. but that’s just my biased opinion.
The path of least resistance will seldom get you where you need to be.
Unfortunately that's what happens with any discussion on caliber choice. Ultimately, a firearm is really a customized tool to fit your particular attributes and skill sets which may follow the mainstream and may not. "Know thyself" is just as applicable to firearms as it is to boxing/martial arts. Overtime you learn how your particular body and mind reacts to extreme stress, and how that effects your ability to perform complex tasks, weapon manipulation, marksmanship, and operating/moving tactically. Everyone reacts differently and exhibits different weaknesses under those stresses, and you should know yours. Sometimes you can at least get a general idea of how your body and mind works if you have been in competitive sports.
As long as you train hard in timed, meaningful courses of fire and train often.......you can pick what ever caliber you want and can expect the platform and caliber to work well for you. At this point in time, it is simpler and easier all the way around to go with 9mm. It will receive first priority in terms of invention, logistics, and product support. In my mind it is also the better choice when it comes to civilian concealed carry which usually involve a compact, subcompact, or micro pistol. I like the heavier calibers, but .40 and .45 suffer more handicaps in smaller pistols due to capacity, durability, and weapon handling.
Last edited by Galbraith; 11-22-2019 at 10:20 AM.
.38 Special from a 2.5" Colt Diamondback worked well enough for Lt. Frank Bullitt - it's good 'nuff for me.