Justright--if the crack is really narrow, try some superglue. My BAS has some small cracks in the handle, and superglue took care of them no problem. You can sand the horn down a bit after you fill the crack. I use 1000 or 1500 grit paper with a little hooflex on the handle-- seems to avoid scratching. If hoof moisture or Fiebings is similar to hooflex ( a smelly gooey mess) you might want to try some, though I think sanding without it would be ok. You could just leave the superglue without sanding if it is a user-- it really isn't that noticeable. Good luck, and let us know how your repair turns out.
--Josh