Brand new G17 somehow got damaged firing pin safety. I ordered new one from USA and after receiving in and changing, the slide wont fit the frame. It seems that new firing pin safety is protruding slightly more from the slide and trigger bar does not allow slide to be placed again on the frame. I reassembled gun with older FPS, and slide locks on the frame as usual. I tried new one, wont go So I used to manually push new FPS downwards blocking firing pin in the slide in its forward position and afterwards placed slide on the frame with out any problem. Standard safety function check is OK. Question is how can two visually identical parts cause such an issue? Is it new FPS spring which must brake in to work properly with older parts or what? Glock is 3rd generation with alpha prefix GLT.