On Paul Harrell’s YouTube channel, he has a couple of good videos, one comparing 9mm to .40 S&W, and another comparing .40 S&W to .45 ACP. The results were instructive.
9mm vs .40 S&W:
.40 S&W vs .45 ACP:
His conclusion regarding 9mm vs .40 S&W is that, even with modern bullet designs, the .40 S&W is more powerful and has better penetration than the 9mm. My personal perception is that, yes this is true, but it’s not enough of a difference in my mind to make me feel undergunned carrying a 9mm, or to make me want to rush out and buy a .40. For instance, the difference between those two is not nearly as significant as would be the difference between 9x19mm and .380 ACP (see below). However, the performance difference between .40 S&W and .45 ACP is negligible; and is much more dependent on things like cartridge/bullet choice than anything else. And speaking for myself, since I already own five pistols chambered in .45 ACP, I still don’t need to rush out and buy a .40 cal.
BTW, Harrell also has a.380 vs 9x19mm comparison using the Ruger LCP (.380) against the Ruger LC9 (9mm) - two very similar pistols from the same manufacturer. In that video, the 9x19 has a very CLEAR advantage over the .380 ACP.
Not meaning to knock anyone’s choices here....including anyone whose primary carry choice is a .380, if that’s what works for you. But it seems very clear to me that 9x19mm, .40 S&W, and .45 ACP exist on a tier above that of .380 ACP. The .380 is a good choice if that’s what it takes to make you actually carry the gun instead of leaving it at home; but in comparing the 4 cartridges, .45 and .40 are tied for first place with 9x19mm in a fairly close 2nd; but the .380 is a distant third place in terms of personal protection. But as I said, the .380 in your pocket beats the .45 you left at home.
That said, the .357 magnum in my pocket beats your pocket .380 or pocket 9mm hands down, by a large margin:
I hope you guys get as much out of these comparisons as I did. But as always, caliber and platform choice is a very individual preference, and what works for one may not work for another, let alone everyone else.
Give me Liberty, or I'll get up and get it myself.—Hookalakah Meshobbab
I don't carry because of the odds, I carry because of the stakes.—The Annoyed Boy