I recently acquired a used Smith & Wesson made PPK/S in 380 ACP. It came with two Walther made magazines, one with the finger rest and one without. I took it out to the range a couple weeks ago and fired it for the first time. The magazine with the finger rest functioned perfectly and I fired over 40 rounds with it. When I tried to use the magazine without the finger rest it will not stay in the weapon. I’m not talking about the known issue where the magazine drops out after firing a shot or two or even falls out if you pull on it. This magazine will not latch in at all. I push it in and it comes right back out in my hand. I should note here that if it is empty it goes in fine. Put a round in it and it is a no-go. I wanted a second magazine with the finger rest and found a new original Walther produced magazine on line. It arrived today and when I tested it the same thing happens that occurs with the malfunctioning magazine that came with the weapon. I have checked the D shaped hole for the magazine release. It is clean and the release is flush with the side of the frame when the button is not pushed. I looked at each of the magazines in the weapon and I don’t see any point where the finger rest or the plain floor plate is making contact with the base of the weapon or the hand grips which would prevent the magazine from locking in. I have stood the magazines up next to each other (and laid the odd one on top of the ones with the finger rest) and I can see no difference. I’m baffled at this point. Any assistance/advice would be appreciated.