Nuts origially before inpregnated plastics, HDPE, Teflon, graphite compounds were bone being Ivory., followed by brass. I too have HBII and 3 other PRS, and they all have a secret Prs compound? Which i am not a fan of as tempreture changes shrinks the slots, and causes binding, leading to out of tune issues; so i have had to widen the slots maginally ,and use graphite powder. (IF you cannot source this crush up a pencil) .You have had success with bone and have been happy so use it, you could allways dye it black. But i have noticed on all my guitars the strings sit not to deep just below the top of the nut; which is correct. Paul said recently, that anything that touches the strings is critical; correct, and now he has employed brass at the saddles; interesting? So maybe he is going back to a natural material being brass , and we might see this again, as a material for top nuts ,as it works, rings, and its bright. I hope that helps you a little regards Stevie
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