When I was young, I made darts from a wood screw, notebook paper, and tape. Put the dart down into a pipe and cut the funnel to fit. (saw how to make it in a Charles Bronson movie, the one where he was protecting the President's wife. Naturally, I made one and shot the heck out of the backyard fence. They shot shockingly well.
Just thought they would really rock with a blast of compressed air.
dOJOWO, your modification sounds like a lot of fun.