I cant view the file, but I was about to program a similar sounding thing tonight...

The psuedocode is in my head, I cant see it to be that difficult.

Did you do it by stepping thru points, like moving it thru its lifespan in one frame? Or did you just check to see if an intersection would occur at a specific spot.. eg. if your checking horizontal collision, you step through the possible objects it could collide with, and then just see if the bullets path would intersect?

I beleive the second would be the better one.. and if you restrict the firing to horizontal it would be stupidly easy to implement.