US Patent 7805877 Inertia driven eye protection for a scope

An eyepiece of a firearm scope includes a spring positioned between a shock mount and an ocular lens, wherein the spring holds the ocular lens a predetermined position from an objective lens of the scope when the spring is in an uncompressed state. During recoil of the firearm, the spring compresses to allow the ocular lens to travel towards the objective lens, thereby increasing an effective eye clearance distance between the ocular lens and a shooter. Following recoil, the spring expands to return the ocular lens to the predetermined position. The spring compresses again during impact of the eyepiece with the shooter's face, thereby partially absorbing the force of the impact and reducing the chance of injury to the shooter.