The vertical distance between the center of a firearm’s bore (the barrel) and the centerline of an attached optic is a crucial measurement for accurate long-range shooting. This dimension is a key input when calculating bullet trajectory, as it affects the point of impact, especially at close ranges. For example, if an optic is mounted 2 inches above the bore, the bullet will initially strike below the point of aim until the trajectory intersects the line of sight.
Precise knowledge of this offset offers a significant advantage to shooters. By accounting for this variable in ballistic calculations, users can predict the bullet’s path more accurately, leading to improved shot placement at varying distances. Historically, this dimension was often estimated, resulting in less precise aiming solutions. Modern tools allow for more precise measurements, which are essential for maximizing the effectiveness of advanced aiming systems and long-range engagements.