Yeah, I checked those part numbers several times, they don't match up with my ferrules from stewmac. It is easy to find the main bit for the ferrule (5/16 diameter hole). But, I cannot find a counterbore cap drill which has a pilot that matches the ferrule hole of 5/16. The closest I can find is this. The pilot hole diameter is just too small compared to the 5/16 hole that the ferrule requires. I must admit, this is getting frustrating.