Bearings are what you might be thinking of. Ball bearing type bushings are designed for high rate of fire (ROF) guns but typically won't stand up to a high fps spring for long. I have plenty of remains of internals in my shop from clients who though otherwise to testify to that. High fps springs should use a good quality solid metal bushing.
ASC & RAAT Age Verifier for Central Alberta
Authorized G&G Dealer.