Ok, here's a question that may seem strange, but I'm hoping someone will have an answer.

I have been through many iron sets over the years and at any given time I have around four or five sets. I've noticed that most irons shafts when held by the club head will ring (or resonate) when the butt end is tapped on the ground. Ive noticed that the ring is higher or lower depending on flex. I'm guessing that this has to do with the frequency of the shaft. I've also noticed that some shafts (even within the same set with same lables) sound dead and don't ring at all and some sound fine. The question; I'm guessing it's the shaft because all else seems fine (grip, furrels, nothing lose that I can see) So... Why do some shafts (within a set of same) have a very dead sound. I gotta figure that somebody has an answer to this. Also, will this have an effect on playability of the club?

Thanks