If you played around with camcreate a bit, you could camcreate a bullet (one with no tracer, otherwise you get strange looking trails) at head level. You would probably have to adjust the variables some, but it should work.
To beta test, you could set up a camera with a setAcctime .5 and see where the bullet is impacting.
Heres an untested script that should get you started
_victim=targetname
_bullet="insertbulletnamehere"
;play with this value to change height
_iheight=1.75
;ensure target is standing
_victim setunitpos "up"
_dir=getdir _victim
_pos=getpos _victim
_px=_pos select 0
_py=_pos select 1
;Create bullet 2m front of target's head
_npx=_px+(2*(cos _dir))
_npy=_py+(2*(sin _dir))
_bullet camcreate [_npx,_npy,_iheight]
;Send bullet back towards target
_newdir=_dir-180
_xvel=(200*(cos _newdir)
_yvel=(200*(sin _newdir)
_bullet setvelocity [_xvel,_yvel,0]
exit
Don't know if it will work, and the cos/sin might be switched around, but give it a try...
-Grendel