Never heard that on a CZ. However, when my dept switched from Berettas to Sigs, the armorers course told us that some Sigs had been shipped with plastic guide rods and some of the flanged ends were reported to have broken off resulting in an odd looking situation. I think I still have a plastic rod in my D PCR, but it's about the only one. I can see where it COULD happen, but I haven't seen it yet.