I have a few pair of chucks. I use them mainly for the purpose to stregnthen my wrists and forearms. Not sure about the bag and chuck thing thou, I guess as long as the bag can take it. I think that if you practiced everyday for about an hour, you can get pretty quick with snapping. But you can also use these for performing locks and holds, not just tring to hit someone, who will most likely dodge your efforts. About the throwing of knives and stars, I would say they are more for hand eye coordination, and playing around like we all see in the movies. Not going to say anything about safety because you sound like your going to use caution. And if you don't the chucks will sting you, not too mention if you stick someone with the dart/star w/e. I stuck a dart in my friend once, it looked painful.