STR_ROBOTURRET_MINIGUN_WEAPON_CLIP apparently.
Now what is that and how do I create it?
Maybe I don't know what I'm looking for but I can't see where the ammo comes from anywhere in this.
Look at the built-in weapons the unit
spawns (as in: it is created that way by the game) with.
Which item
s does the drone spawn with when the game loads that map tile?
EDIT:
As far as i can tell this is bugged at the moment, there is no way to actually load the ammunition into the weapon. This needs to be fixed. You can do this yourself for the moment by copying&pasting the necessary attributes from the clip to the weapon iteself, starting with "power: 35" and ending with "clipsize: 256" (so the lines include power, damagealter, toarmorpre, damagetype and clipsize). Simply append them after the last attribute of the weapon (though it doesn't really matter at what position you insert them).