There’s no such thing as “knock down power”.
Says who? I've seen several people shot with a .45 and all of them died. Seems to me it knocked 'em down just fine.
I would have to agree with that except for the .45 for obvious reasons. The problem is you really only get one good shot. A 9mm holding 15 Critical Duty is heady stuff. Who cares if it can penetrate a car doors and windows. That’s cop stuff.
I don’t know about relative knockdown power of various handguns rounds, but I came to the conclusion working in an ER in DC during the 80’s, that you can’t kill a drug dealer with 9mm. They adsorb the stuff like a sponge, take a short holiday in the hospital and then get back to work.
There are a lot who will disagree. Care to expound upon your assertion?