No one can give you an informed answer without the calibre, powder charge, and bullet weight, and height of sights above axis of bullet. At 30 yds. the bullet is on an upward trajectory because it has to rise to the level of the sight plane. Where it impacts down range depends on velocity and bullet aerodynamics/resistance. You may be able to find a ballistics table online for your particular gun, but to dial it in at 100yds. you need to take it to the range.