Do NOT ever trust your life to a PPK if you can avoid it. I had a PPK/S and even has a gunsmith all through it. It is NOT a reliable pistol AT ALL. I have heard countless other stories of poor reliability. Mine was so bad I gave it to one of my friends - he has hundreds of firearms and this would not be used for anything important.
If you want that sort of 380, the Mauser HSc or SIG 230 are far and away more reliable. My father has a beautiful HSc and its reliability is sterling.
That all said, if you insist on going with 380, a choice I am strongly against, then you should roll your own ammo and load right up to SAAMI maximums... or at high as the gun will reliably feed. A super hot 380 will perform somewhere in the 9mm Parabellum range - very anemic.
If you are going for a semi, then I strongly recommend 38 Super, 40 Smith loaded as hot as it will go, or .45 ACP. The Super has ballistics very comparable to 357 mag. If you have a 10mm frame, you can put a .40 slide and barrel on, say, a 1911, load the 40 "long" and get 1560 fps with a 130 gr. slug - that is SMOKIN' hot. The 40 Smith brass is actually stronger than that of 10mm and will take the pressures.
Also, when looking for a gun for self-defense, look for one that has a very low barrel centerline. High centerline pistols will roll more when recoiling. The H&K P7 is perhaps the lowest centerline pistol out there and it is noticeable when shooting. One of the highest is the lousy Beretta 92, which is nothing more than a re-styled Walther P-38. Lousy gun and $$ to boot. They roll like crazy and are therefore harder to get back on target - a VERY bad characteristic in a self-defense weapon. I am no fan of Glocks, but in this respect they are well designed with a very low centerline.