Jaywalker,
that's what I said leave it to that.
The .40cal was developed as a law enforcement cartridge designed to duplicate performance 10mm(FBI) in reduced velocity.
Since the popular infamous miami shootout back in the eighths there was a concern about the 9mm.
The 9mm pistols and ammo keeps evolving since then so it is the .40cal so the argument would be more about how many rounds a LEO can train / year.
Initially it was found that a 180gr will deflect less through glass and metal barriers (a great concern at traffic stops going bad) so it was slowly shifted towards that round but again the 9mm didn't stay stagnant. What those rounds and pistols did then vs. today specially with the new training (And I said training, not hardware) this would be a different story but nobody really knows.
By the same token SIG-Sauer responded to similar requirements by some austrian police and in collaboration with Federal they created the 357SIG which is superior to both the 9mm and 40cal. It is expensive but it is pretty good at replicating the 123gr 357 magnum which is amazing in a autoloader with 15 rounds. It is expensive but the local police here has them (we pay a lot of taxes - lol)
So, with a good pistol today, and the best carry ammo, all good stuff one way or another anyway. Any of those but the 25ACP but hey, if I had to choose between that and a rock I would probably go with the 25 or even the 22LR.
So again, going back to the real state issue. Placement is the key.
Train a lot, get good at it and pray to god you never have to be in a position where you have to use a firearm to defend your life or a love one or somebody defenseless.
Also pray that the headless politicians start downsizing the bankrupt system from the top and not at the bottom so they do not have to fire teachers, close libraries, schools or let go policeman or firefighters or emergency responders so they can be there to defend us from criminals and thugs and take us out of a burning building and keep our kids education for a better future.
That way maybe one day we will never need to carry nice pistols or great ammo anymore.
Cheers.
E.