So if you shoot 90 degrees up from horizontal, ie straight up in the air. If there was no wind what so ever, the pellet would never cover any horizontal distance so would never fall? False!
You are applying an upward vertical force which will only cease once gravity has increased at a rate of 9.81ms2 at which point the 2 forces are equal and gravity takes over and the projectile will begin to fall under gravity's force.
(not taking into account drag)
Here is some good reading.