It's not that there is no difference. It's that "knockdown power" or "stopping power" is a fantasy. Physics says unless your pistol is knocking you on your ass every time you fire it, it won't knock the person at the other end on their ass either (See Newton's third law).
The only two ways you reliably end a gun fight are scoring a CNS hit (shutting the bad guy's brain housing group down) or causing enough blood loss that they expire.
CNS hits are a beautiful thing when you make them. It's like someone clipped the strings on a puppet. They are also hard as hell because the head moves around a lot.
So we're left with trying to exchange enough blood for air in the bad guy's body to cause them to expire. The most efficient way to do this is to poke a lot of holes in the bad guy near the pump and the major pipes that exchange and carry their blood (read as; Center chest).
You don't need a hand cannon to do this. You need rapid, accurate shots into the targets ten ring.
You can do that with a 454 Casull? Rock on brother. You love the 1911 in .45? Well do it to it. You shoot a Glock 19 best? Awesome. You really like the Bersa .380? Make sure that bitch runs and then run the hell out of it.
At the risk of repeating myself: Carry what you can shoot well, just so long as you carry.
Arguing 9mm vs. 45 (vs. 40 vs. 10mm vs. .357 sig etc..) is a waste of bandwidth.





