Have you ever read any F. Paul Wilson, AF? He writes the Repairman Jack novels.
Well, in one called Hosts there’s a scene where Jack is riding the subway in NYC and just happens to be in the car some psycho has chosen as the site for his mass killing. Jack is armed, he’s ALWAYS armed, but he doesn’t act immediately. You see, as far as officialdom knows Jack doesn’t exist. He’s a ghost. Has no SS number, has never filed a tax return, like I said, he doesn’t exist. Getting involved in this could screw that up royally and land Jack in prison for perhaps the rest of his life.
So he hesitates, hoping against hope that one of these citizens will rise to the occasion and TCB.
Of course nobody does and so, while shouting “Shit, shit, shit!’ Jack draws his Semmerling LM4 from an ankle holster and goes to work. The Semmerling is a .45 but not a true automatic. You have to rack the slide manually for each of its 4 shots. Jack does his thing, puts the psycho down, and after policing his brass excoriates the rest of the passengers for being such sheep and just walks away into the night, hoping nobody gives the authorities a good description.
So, he took the guy out, policed up his brass and disappeared into the night.
The book is an entertaining read. I highly recommend it.