I can't believe no one saw and answered this thread............ You may find this shocking but since I have never made a bead head nymph or a cone head fly, I can not be of any help with this question. The bead & cone head thing came along after I had been set into motion. I still make flies the same way that I learned many years ago and they still work so I never went to the weighted heads. I used to put those zinc eyes on Bunny Fur Comets but got way tired of getting snagged on the bottom so I have not used them for years now.
Sorry, next question