In practice, if the target is not far away, the distance over which the bullet falls (as compared to go in a straight line) is rather small.
To give you an idea, assuming the velocity of the bullet is ~1000m/s, and the target is 100 m away, this will take the bullet 0.1 s to reach the target. In 0.1s, it will also fall g t^2/2 = 0.05 m = 5cm.
cheers,
Patrick.
PS:
http://hypertextbook.com/facts/1999/MariaPereyra.shtml