I find that the problem with Morph props, although I have created many of them, is that in iClone 6.5x and earlier (one might be able to imply something additional from that statement) Morph props were done via Face Puppet which, in my opinion, limited some of their application because, as far as I know, you can't set Face Puppet values...you need to apply them by mouse movements. For example, in my Bow (which was a Morph Prop) the arrow was an independent prop. Since the Bow was drawn and released using Face Puppet the motion was not completely linear which made it more work to sync the arrow with the draw string. In contrast, my Crossbow was implemented using bones and thus the draw action can be linear which makes it much easier to sync with the independent bolt action.

Going back to the OP, once the arrow/bolt is fired, could one not use iClone's physics to take care of the flight? I haven't tried but you should be able to make the arrow/bolt a physics object, enable gravity on it and then set up an initial force to propel it. iClone should take care of the rest until impact. Just an idea.

"We often compare ourselves to the U.S. and often they come out the best, but they only have the right to bear arms while we have the right to bare breasts"
Bowser and Blue, Busting The Breast