There are lots of people that never grasp the following:
If you fire a bullet from a level barrel and at the same time simply drop a bullet (both simultaneously from the exact same height), they will hit the ground at the same time - one just happens to hit way out there and one at your feet.
What if the gun is a magnum shooting a liteweight bullet?
Makes not difference. Galileo Galilei proved that 400 years ago by dropping stuff off the leaning tower of Pisa.
If you're talking "way out there". There's a couple of monkey wrenches to consider. The first is Coriolis Drift if firing a rifled barrel, depending on where on the earth you are and in what direction you're firing; Litz on the Coriolis Effect Coriolis Drift can have a vertical component to it that opposes the forces of gravity.
The other factor is the curvature of the earth. The farther out you're shooting, the curvature of the earth causes the drop distance to the ground to increase.
BTW, Galileo found that the heavier ball hit the ground first. Galileo's experiment
