Actually, the Wild Hare hardware pack hasn't ever contained the "A" nuts to my recollection. There really isn't a need for them. If you feel uncomfortable about the "bareness" of the shaft, you can add a flat washer and a hex nut to perform the same task.

The load on the horn shafts isn't as much as one may think on these planes, and everything holds up exceptionally well over the long term.

Pat