Your question is relative. Lighter, faster bullets will be flatter at shorter distances, but they usually have lower BC's and start to loose velocity quickly down range. Trajectory is based on velocity and BC and down range velocity is based on BC.

So the question is are you talking trajectory out to 300 or 400 or 500 yds, etc? And what is the velocity and BC of your bullet?

Like Grit said, you should crunch the numbers in a ballistics calc to get your answer. Here's an easy one to use...

External Ballistics Calculator