Greetings.
"removeAllWeapons this" will cause the AI unit to instantly lose their weapon. If you want them to actually drop it, you need to use the action command.
unitName action ["drop weapon", weapon]
unitName action ["drop magazine", mag]
I think. It might be completely different to that, so correct me.
-Supr. Cmdr. PsyWarrior
-Psychic Productions