A LOT of shootings involve on hit or less. So for a LOT of shootings, the bigger caliber would have an advantage.
Do you have a basis for that statement?
For
fewer than one hit, the question is moot. No injury is sustained.
But how about
one?
One reason that it sounds counter-intuitive to me is that police training calls for the immediate, rapid firing of several shots, and that is consistent with the teachings of civilian self defense trainers. S the fusion becomes one of how many incidents actually do involve a single hit.
Another is that to stop firing willfully after one shot, the defender would have to have reason to believe that his or her first shot had been sufficient, and in a short range incident with a violent attacker closing rapidly, it would seem
extremely risky to make and act on such an assumption.
In the chapter on wounding mechanics
In Defense of Self and Others... Issues, Facts, and Fallacies: The Realities of Law Enforcement's Use of Deadly Forceby Urey Patrick and John C. Hall, the authors state that a common reaction to a person being stuck by a bullet is--
nothing--
no immediate reaction. The authors go on to describe why police training prescribes the shooting of several very rapid shots at the outset.
This discussion has nothing at all to do with caliber selection or such things. Rather, it is based on numerous real world observations framed in a discussion of what lawfully constitutes reasonable force in self defense, as it pertains to Fourth Amendment cases--42 USC 1983 litigation (civil claims for a deprivation of rights under color of authority.
Specific to the subject of the thread, however, the authors do describe what is necessary to effect a physical stop. The do take the time to discuss why, in their opinion, a single wound from a .45 would be
somewhat preferable to a single hit from a 9MM.
But they go on to explain that reliance on a single hit would not be at all prudent, and to extoll the advantages of "more, deeper, bigger holes."
I recommend the book.