When I fire a multi-round burst from the Vulcan gun, how come the ammunition counter is only reduced by one?

A minimal burst of fire from the Vulcan shoots off 5 rounds of ammunition. The Vulcan's ammunition counter measures the number of ammo bursts remaining, not the actual number of remaining bullets. So when the ammo counter is initially set to 500, it means that there are 2500 bullets remaining (500 bursts of 5 bullets each).