I'm not familiar enough with the PPK itself one way or the other to make a recommendation.
I do carry a .380 on occasion, and lately I can tell you it's NOT because ammunition is so plentiful and cheap. It's quite the opposite. I'm guessing that you mean "plinking" rather than "target" use? (most .380s aren't known for their accuracy). If that's the case, I'd suggest you go with a 9mm or a .40. Not as concealable, but far better ammunition availability.