Elites drop double the ammo that their normal, non-elite variants have.
For example, a minigun-wielding elite former captain would drop a 200 10mm clip, compared to the normal former captains dropping 100 10mm bullets.
Former sergeants drop 30 shells and elite former sergeants with a double/assault shotgun drop 60 shells.
Former humans drop 24 10mm bullets and elite former humans drop 48 10mm bullets. Catch my drift?