Abstract: An adjustable iron sight for firearms includes compensation for projectile drop. The projectile drop compensation moves the sight aperture to compensate for projectile drop. Use of the compensation will allow aiming directly at the target without having to visually compensate for projectile drop. The projectile drop compensation mechanism includes a multi-position manually operable wheel and cam that is profiled to match the trajectory of the particular firearm and load. As there are many possible loads that could be used with a particular firearm, the multi-position cam is interchangeable to allow changing to a cam that is matched to the specific load that is desired.