A projectile fired horizontally will hit the ground at exactly the same time a bullet dropped from your hand will hit the ground. By calculating the amount of horizontal drop of a fired projectile, you can determine the amount of compensation needed to hit the target’s bull’s-eye.
To calculate the amount of time required for a bullet fired downrange to hit the target, use the following relationship:
travel time to the target: t = d/v
t = time (seconds)
d = distance to target (feet)
v = velocity, which is specific to each firearm (ft/s)
To calculate the vertical drop of a fired projectile over time, use the following relationship:
Vertical distance dropped: d = 1/2 gt2
d = distance
t = time (s)
g = gravitational acceleration 32 ft/s2
s = seconds