I recently came into a very nice pre-war M&P Target. While cleaning the hammer in the midst of my usual look under the hood I felt something tiny fall through my fingers. Uh oh. The pin that secures the double action sear to the hammer was gone. An hour on hands and knees with a flashlight revealed some dead spiders and spent primers but no tiny pin. But wait, there's that cylinder bolt plunger that I lost months ago. I wonder...yes, the pin is exactly the right diameter and length, minus the smaller diameter portion that the cylinder bolt spring fits over. A few minutes with a file and presto, a pre-war, double action spring replacement. That sinking feeling I had when considering where to find a replacement pin for a 90 year old revolver vanished. All is well.