Got a book (somewhere) that I bought at a Street Survival seminar our Chief sent two of us to back in the early 80s.
Lots of pictures and incident reports.
One picture is of a guy lying on the slab in the mortuary shot either 17 or 19 times with 9MM before a State Trooper sneaked up on the guy and shot him in the heat with a 12 ga/00 buckshot.
Another is a motorcycle gang hit man that tried to kill an IL State Trooper. He missed the Trooper. The two troopers in the car hit him 11 or 12 times and he walked to his bike, got on it and was trying to get it started when he fell over dead.
Yeah, the FBI shootout. One of the agents was on an FBI competition pistol team. He hit one of the bad guys (as the guy was getting out of his car after another FBI agent/car had run them off the road) with two 9MM hollow points right under the left arm. The bullets failed to make it to the heart although one did cut an artery that would have resulted in the armed robbery suspect being dead at the scene. But not till after he'd killed a couple FBI agents, crippled one for life, wounded one or two more. He was killed by the agent he'd shot through the arm/wrist (crippled for life) at spitting range with the agents .38 special and head shots as he'd gotten his wounded partner into one of the FBI cars and was attempting to start it and leave.
Yeah, we never considered the 9MM (we got all the reports, annual and monthly of police officers killed, officer involved shootings, etc.) and we went with the .357 magnum and 125 grain hollow points.
I'm not saying the FBI didn't get it right this time. Maybe they did. I'm just saying I remember the first time they said it and some of the results.
I can't say a .40 is any better. But it is a bigger bullet. And some of them shoot so darned good.