ballisticsAnyone who has ever tried to shoot a target that is at a substantial angle from horizontal (e.g. 30+ degrees above or below) has quickly realized that to hit it requires aiming below the target. It makes sense to me that this would be the case when shooting at a steep downward angle, but it’s not so clear why it would be when shooting upwards. It seems to me that when shooting upwards one should have to aim high.
It has to do with the fact that while the bullet is traveling a certain distance, the vertical component (due to gravity) is less. Think of a right triangle & the Pythagorean theorem. If a bullet is traveling horizontally, parallel to the ground & perpendicular to the gravitational pull, the effect of gravity is more than if shooting at a high angle of incident. A good technical explanation can be found in Robert McCoy’s “Modern Exterior Ballistics” book.
A couple more detailed resources:
This has to do with the ballistic path the bullet is going to follow. As the bullet flies (on a shot with ~0 elevation change), 100% of gravity’s effect on the bullet is going to be “downward” as the sights are concerned, i.e. 90 degrees away from the shooter. In a significantly downward or upward shot, a good portion of gravity’s effect is going to be back toward (when shooting up) or away from (when shooting down) the shooter, as opposed to “down”. The sights are compensating for 100% of that gravity’s effect, so they’re actually overcompensating when the shot has a significant elevation component. Therefore, you aim low.
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