Did you discuss your theory of carrying a gun with minimal stopping power but maximum concealabity like a .22 with him (Ayoob)?
A person with a 22 automatic can get the hits and bring down the target, but there are a couple of problems.
1. A person with a 22 has to have laser-like focus on getting the hits. Hit the target in the head or neck. Most people can do it, but it takes more skill than just getting a center of mass shot.
2. Twenty twos are notoriously unreliable in terms of function. I know one man who carries a walther P22 and it is 100% functional. I know another who bought the same kind of pistol for the purpose of putting a legal silencer on it, and it just never worked right for him.
Stick with a 380 or larger and shoot for center mass.
I don't seriously advocate a .22, my point was against focusing so much on stopping power that you get a gun that you wind up never actually having on you
And when I took his first course, the gun I brought with me was my .38 snubby. Ayoob was impressed that I managed to pass the police qualifier with it, including the 25 yard range part