I was sitting on the couch just kinda tapping an un-loaded pipe with my finger. I noticed that a flick with the fingernail made more of a lighter "tink" kinda sound. Then I tapped another pipe and it made more of a deep "thud" kinda sound. Then of coarse my OCD kicked in and I tapped many other pipes (all unloaded). I noticed that all my best smokers made the "tink" sound, and the not that great ones made the "thud". Totally not scientific, but got me thinking is there something to this? Could it be like squeezing fruit? It would make picking pipes out simpler, if your at a place where you could do this. Sounds crazy, but I bet many of you will be tapping your pipes now!