[Pikachu_Dad]

If we add in the angle.

horizontal terms
Sin(ang)=vert/fps. cos(ang)=dist/fps

So. Fps*Cos(ang)= dist (ft/sec)
Time= distance/dist = distance/(fps)*Cos(ang)

Vertical terms
Initial vertical velocity (fps) = fps*Sin(ang)
Less acceleration due to gravity = a = -9.8 m/s

Velocity = integral ( a dt) from t to to = at + Vi. = fps*Sin(ang) - 9.8 m/s * t

Then height is. Integral of above = Vi t - 9.8/2 * t^2. = fps*Sin(ang) - 9.8/2 * t

[Pikachu_Dad]

Assumed target was at same height as gun.

So an angle of about 0.84 is needed.

[editor-surveyor]

So you didn’t mean drop.

Really, his assertion is not so improbable when you consider that he had all the time in the world to sight in, and all he need do is get close and the balloon is history.