. . . There you have the reason why pistol caliber debates go round and round interminably. Everyone wants something that does not exist: a pistol cartridge that is small enough to be practical and is also highly effective.
At the same time that the military is making noises about going to a bigger pistol caliber than 9mm, the FBI is talking about going back to the 9mm, giving up their present .40 S&W pistols. A difference worth noting here is that the military mostly shoots FMJ while the FBI uses expanding bullets. But there is a sameness too. Arguments about pistol effectiveness are debates over very little. That is to say, pistols have little effectiveness to debate. The numbers can be jiggered any way you want, of course.
|L: .45 ACP; R: 9mm Parabellum|
"Yeah, but..." ran the counter argument, repeated so often that the words were soon running together into the familiar refrain "yabbut, yabbut, yabbut..." The 9mm bullet is faster, and also lighter, so it sheds its kinetic energy all that much quicker in the target...
Uh huh. One of the things you learn in the gun community is that if an argument can be made it will be made, whether or not that argument is outstanding for cogency.
In fact no practical type of pistol does what we would like, which is to stop an attacker reliably and instantly, every time. That fact is the little lost dog in the caliber debates, constantly running about and trying to be noticed, wagging, sitting, rolling over, trying in every way to be ingratiating but being roundly ignored.
The only reason to use a pistol to defend yourself is that you did not bring a proper self defense firearm. The pistol is the hardest of firearms to shoot straight, consequently has the lowest hit probability, is not very powerful in any manageable, practical version and its performance against modern body armor is roughly nil, though surely no less than that. The way a pistol stops the fight is by good hits, and those are difficult to obtain with a pistol. There you have the reason why pistol caliber debates go round and round interminably. Everyone wants something that does not exist: a pistol cartridge that is small enough to be practical and is also highly effective.
The 9mm cartridge has several things to recommend it. Its recoil is only moderate, at least in a full sized pistol, and is something a recruit can learn to manage in a brief course of instruction. Its use in many wars in the last century proves it is not useless, but generally satisfactory if your expectations are not set too high. (It performs just like a medium bore, medium intensity pistol cartridge.) It is lighter to carry in quantity than the .45 or the .40. It makes a usefully bigger hole than the .30 Mauser and 7.62 Tokarev pistol cartridges. This mix of virtues has made it vastly popular and, thus, ammunition is available in many parts of the world.
The debates continue, and will continue. So long as people look for something they cannot have, a pistol cartridge that is really appropriate for the job they would like it to do, their minds will continue to invest largely imaginary advantages into this or that cartridge, and in doing so they will provide material for gun writers to produce endless vapid articles about it.