Should I be using BFB tune? If so, what is the difference with BFB tune versus BFB Autotune, (BFB.U and BFB_Atune.U)? I have a 5977B MSD. I am currently using the Extraction Source Tune (Etune.U) My spectra does not always match well with the NIST17 library. I am doing a lot of volatiles work.