that's easily done, put this in the condition field of the trigger:
nameOfUnit ammo "Weapon" == 0
nameOfUnit is, as you've surmised, the name of the unit in question
ammo is the command which returns the number of bullets left in the magazine. "Weapon" is the name of the weapon being used, for instance "M16" or "Ak74" (full list available in the Editors Depot/Tutorials/Weapons, command and object lists section
). The == 0 means the trigger won't fire 'til there're 0 bullets left in the clip
If, however, you're going on the multiple magazine thing...i.e only stop when you've got NO ammo (as in you've got more than one magazine) whatsoever left...well, that can be done too...I'll even tell you, but only if you that's what you need
/wasting space
g'luck!
Wolfrug out.