During my law enforcement tenure I carried both the .38 Special and 9mm and both were consistently poor performers. I am personally aware of incidents in which one suspect took six rounds at handshaking distance and then walked to the ambulance, and another (a psychotic acting out with a knife in each hand) who took six rounds from three officer's sidearms, went down, got up and charged them again, took another six rounds, went down, got up again and took six more rounds before he went down and stayed there, dying later in the ER. For the mathematically challenged that's eighteen rounds delivered across the distance of a residential room. If that had been a lone officer instead of three he'd have been dead.
I hear the arguments here about improved ballistics of these calibers but my experience is real-world, not academic, and I don't trust them.
The problem with anecdotes like this is that they imply that if something stronger were used-- say .45, .357 sig, or 10mm-- that the BG would have instantly dropped.
Logic doesn't quite work that way, even though our emotions do.
There are plenty of anecdotes of BGs absorbing lots of .45 as well--though I suspect a good bit fewer anecdotes, but extant just the same.
In situations like the one described above (18 rounds) I have to wonder about the role played by shot placement. You simply can't blame the caliber for failing to make glancing shots or even COM hits into that rare breed of instantly capacitating shot.