[Tyhm]

It's ironic that projectiles were designed to be used with Classic Style Arrows, and that last check they didn't work with Classic's "Firing Through This Wall" genre. IMHO arrows ought to bounce of certain walls and soar over certain obstacles (bushes, pits, fences), but that's a fair degree of coding that ultimately isn't worth it.
Well, maybe not. onwall and in(this set of statically defined "wall" ids) takes about as much effort. Maybe more processor time? Who knows.
An ordered In would take log(n) time to burn through, on the other hand, but then we find ourselves asking for Stefan to create another command just to make Classic's arrows work a skoch better. It's all very silly.