As far as I can tell, compatibleAmmo doesn't affect the weapon needing ammo, only clipSize does. You can have an infinite-ammo weapon or one that requires some sort of clip.
Well i think it does. I tried to mod laser weapons to recieve a booster pack that would increase power for a shot or two, but leave the weapon with unlimited ammo normally. So i left the clipsize alone and put compatible ammo for it. In battlescape it looked like a normal laser rifle, but i culd not shoot with it until i loaded it with a booster. I fell back on the exchangeable battery laser idea with 2 kinds of clips.
