In many texts around the web, you’ll find one common incorrect explanation of this phenomenon: a simplistic approach derived from the formula used to calculate compensation. You may have read that your shot will land high because, when shooting at an angle, gravity has less effect on the bullet trajectory, since the horizontal distance traveled by the bullet it’s shorter. That’s not exactly the case. The amount of drop due to gravity is not a function of distance, but a function of time of flight, which remains constant because the linear distance to the target is the same. Actually, when shooting at an angle, there is a small change in drop due to gravity, which slows down a climbing bullet and accelerates a descending bullet, but its amount is negligible.

The accurate explanation for why the bullet flies high derives from a perspective fact. To fully comprehend this, you need to understand the difference between bullet drop and bullet path. Bullet drop is the distance from the line of departure to the bullet trajectory at a given distance. Drop is measured vertically (as with a plumb-bob), irrespective of the line of departure angle.

Bullet path on the other hand, effectively is where you would see the bullet along its trajectory, through your aligned sights. The distance that we can measure between line of sight and bullet trajectory (so it can be positive or negative), but it’s always measured perpendicular to the line of sight. This difference is the key of the concept, and you can see why analyzing the image below: