The 45 is effective, but no handgun cartridge is a reliable one-shot stop. In my case it took 3, including a rather messy one.
Frankly, I would have preferred the 12ga with 7's in it for that one-shot zombie stopper.
Under stress it is much easier to get into action, and even though placement is still important, it is not as critical as a handgun.
There's not much money in it, but there's a lot of real estate in the US where that sort of horror almost never happens. Like the low crime-rate areas in Ranch country for example.
Of course, I'm the kind of guy that thinks all cities suck.