You can see a working example of a Blueprint projectile in First Person Blueprint template, if you want to play around with it. There is also a tutorial for a very basic setup that you can view here:
http://www…com/watch?v=ojvuTz4KCfE&feature=share&list=PLZlv_N0_O1gaCL2XjKluO7N2Pmmw9pvhE&index=99