For those who still can't visualize this, Mythbusters did a great "bullet dropped versus bullet shot" comparison and demonstrated the concept perfectly. It is on Netflix for those so inclined.
Maximum Point Blank Zero is how I recommend any 300yd or in hunting setup with a standard centerfire caliber and barrel length be zero'd. We deal with this a lot during rifle sight in clinics at the club (for gun deer season but the bullet doesn't know what it is traveling to and *hopefully* hitting). Once you go past that you likely need a *calibrated* BDC reticle or a MOA/MOA or MIL/MIL scope capable of quick adjustment of the turrets. Personally I don't care much for BDC reticles as a MIL DOT system is superior IMHO.
For those who are really interested in the subject matter, there is no better book than the 2nd edition of Bryan Litz' "Applied Ballistics for Long Range Shooting."
And since several people mentioned it, if you have the ability to shoot out to where your bullet is just starting to go trans-sonic (around 1340fps is a good target) you can "true" ballistics calculators to your load/gun. So no need to shoot at varying distances per se, many quality calculators will allow you to perform this single test to bring the results in line with reality.
And that is the most important part - "the bullet doesn't lie."
