For the purposes of completeness, it should be pointed out that bullets are
not strictly free-falling objects. A high-velocity rifle bullet fired
horizontally, for example, will typically rise during the first half of its
flight (approximate). So, even though it is fired horizontally, the path is
similar to what one would expect if a free-falling object were launched at
an upward angle to the ground. Such a rifle is therefore "sighted in" at
two points: once in the first half, and again later on in the second half of
its flight. It hits "low" at points prior to and after the sighted in
points, and high in those parts of the path that lie between the sighted in
points. That has nothing to do with the thrust of the discussion, but the
repeated references to a "falling" bullet are misleading.