A method for shooting a projectile weapon involves determining the inclination of a line of sight from a vantage point to a target and a line-of-sight range to the target, then predicting a trajectory parameter at the line-of-sight range, for a preselected projectile. Using the trajectory parameter, an equivalent horizontal range may then be determined, wherein the equivalent horizontal range is the range at which the trajectory parameter would be expected to occur if the projectile were shot from the vantage point toward a theoretical target located in a horizontal plane intersecting the vantage point. The equivalent horizontal range may be utilized to compensate for ballistic drop when shooting the projectile weapon. The method may be embodied in a handheld laser rangefinder including a memory for storing ballistic data. Systems for automatic hold over adjustment in a weapon aiming device are also disclosed.