Take this for what it's worth - one person's episode.
Went into a cafe with six family/slash friends. New Year's eve so we waited on a table. As our table was being cleaned, two guys walked in and sat down at the table. I went over and politely told them they must have missed us waiting. One guy pulls up his shirt (drunk or doped up) and showed me a large auto. I turned around and not wanting to yell fire in a theater, told the people we would go to another place. The big guy at the end of the our line said something to the perps and I told big guy to shut up and leave.
As we were going back to the lot, the big guy knocked on the window (still not knowing he had a gun) and said something that sent BG#1 outside to confront me. I held my hands up and told him I did not want any trouble. He turned and walked toward the car BG#2 had retrieved and #1 was pulling his pistol at the same time I pulled a North American 22 mag out of my pocket, firing at the same time he started shooting. He shot several times wildly at the big guy as I shot at him (10 yards). He wheeled around and shot at me then, seeing he was not the only one in the fight with a gun. I got off another shot as he ducked and got in the car.
My wife in the mean time had ran to two cops she had seen next door and alerted them (before the shots rang out). The car passed them and then me as I got a .38 Colt snub nose six shot out from the car. The Police fired their glocks as I shot.
End of story - the perp shot 8 shots, I shot 2 from the N.A. and 5 from the Colt (yes, I had two speed loaders), and the Police shot 7 times apiece. NO ONE HIT ANYONE IN 29 ROUNDS (no blood in the stolen car that crashed 500 yards from the cafe and they left on foot never to be found). Start to finish 45 seconds max.
TO FALs POINT, the N.A. did it's job, causing the BG's to break contact but I think about it 15 years later. I now carry a few different small auto's but the hot weather keeps you from carring anything heavy. I constantly second guess myself.
Yes I am proficient with all my guns as I am sure the Police were. Moral to long story, IT AIN'T EASY SHOOTING SOMEONE WHO DOES'NT WANT TO BE SHOT.