The Manchu used them for different tasks. One reason, on the hare fork arrow I mentioned, is that many small animals are preyed upon by hawks, etc that screech. That screech causes an instinctual freeze response, leaving the animal right where you want it. They were also used for signaling in military maneuvers, target practice, and oddly enough, corporal punishment. Someone to be punished in such a way would be tied to a post and they would take turns shooting at their backside with these arrows. It wasn't a very fun time, as you can imagine.
You can look up the Fe Doro site and see more about it.