Abstract: A riflescope is disclosed which is manufactured from impregnated carbon fibers so as to be light weight, exceedingly strong and have essentially a zero coefficient of thermal expansion.

Abstract: A lock ring prevents inadvertent rotation of a rotatable focusing eyepiece for an optical instrument. The ring is disposed on the device and is fixed against rotation. A face is provided on the ring which is adapted to frictionally engage the eyepiece to prevent inadvertent rotation thereof. The ring is movable or deformable to disengage the face from the eyepiece for focusing.

Abstract: A riflescope is provided with an auxiliary optical system for forming an internal image of data or information disposed outside of the normal eyepiece field of view. A primary application of the system is to transfer an optical image of a target-range figure marked on an external adjustment knob for viewing at the periphery of the field of view without interference with or cluttering of the target image.

Abstract: A riflescope elevation adjustment assembly which reads directly in terms of target distance in addition to providing conventional "click" elevation settings. The assembly includes an adjustment knob which is externally accessible for rotation without use of tools or removal of parts. A distance scale, appropriately calibrated to the firearm and ammunition in use, is displayed on an annular flange extending from the knob to be positioned within an annular housing secured to the riflescope. The distance scale is viewed through a transparent portion of the housing, and is visible when the firearm is held in a normal aiming position.