I used to be a diehard Prang 6mm lead -lover....but the cores *constantly* coming loose had me running for something else. OMYA has a similar product *and* in a hexagonal shape...so they don't go rolling everywhere. (6mm lead - FANTASTIC for little and big hands)...that comes in a class set of 120. I usually buy mine from Nasco.
As for all you "do it myself" pencil sharpeners out there....I'm glad to hear I'm not alone. About half way through the year I can usually designate one or two students in class to be the guardians of "sharpening" - this is after they've successfully demonstrated how not to abuse the poor lead(s). I don't think it's crazy...it's those little details that keep us sane.