If I had a know security pin lock at hand, I'd check it out as have a few contact microphones that are perfect to delve into something like this. Certainly wit

If I had a know security pin lock at hand, I'd check it out as have a few contact microphones that are perfect to delve into something like this. Certainly with spectrogram and zoom in after doing high quality recording and soon see what sticks out. Of course would really need a lock in which you have each type of security pin and a normal pin and change that one pin and compare several unlocking. I'd be supprised that there isn't some distinguishing aspect due to shape changes in the pin altering how it responds to vibration. Yes the springs will have some influence, a small scratch in the pin barrel would have a small nuanced effect that with with right measuring, would show up. I'll put it on my winter project list, more so as it may open up the possibility of not even needing a working key and just inducing some sympathetic harmonic with the pin types to induce resonance that can be measured. Could be a fun winter this year.