To make an AI Vehicle auto-rearmed, its currently needed to order it "Rearm at" .. or, if its Stationary, to : Remote Control it, fire from it's weapon and select the "Rearm at " .. Action (so without Zeus, non-Autonomous Vehicles can't be AI-rearmed) ;. Only then, as long as the vehicle and ammo is within some range, the AI will keep rearming .