Do you have the socket in the horn already? If not, take a 1/2" spare bit and grind the corners so it is shaped like this(>) and use it to drill the socket in the horn. Then, trace the outline of the bit on the bow tip, back and sides and shape the tip in a conical shape. With sandpaper sand both the bow tip and inside the socket until they fit tightly. Now, shape the horn tip to your liking and glue them on.
I'll get a few pics later of the spade bit I ground for this.