- Duane "Buck" Buckner describes parallax and how Aimpoint red dot optics are "operationally" parallax free. 

Operationally Parallax-free optics allow the shooter to achieve accurate hits on target without the requirement of a consistent address to the rifle. Parallax is essentially error in the transmission of light through the optic to the shooter resulting in a shift (sometimes significant) in the presentation of the dot (or reticle) on the target. In an optic that experiences this phenomena, the shooter must establish a consistent cheek weld in order to receive accurate information. In that circumstance, if the dot/reticle appears to the shooter it may represent a dangerously inaccurate aiming solution.

Conversely, in an operationally parallax-free optic - such as an Aimpoint sight - the shooter can trust the reticle no matter how they find it. A proper cheek weld is not required and accuracy is not compromised if the rifle is poorly mounted.

A rifle that features an Aimpoint optic and is properly zeroed gives the shooter great latitude in the employment of the weapon in any operational environment. Find the dot on the target and press the trigger.