Abstract: A range finding gunsight suitable for military usage is provided having a rear portion with a baseplate member mounted for windage adjustment and having an integral upright member provided with an elongated oval shaped aperture. A slide member having a conventional circular peep aperture is mounted on the upright member and is vertically adjustable, the portion of the oval shaped aperture above the slide member defining a variable length sighting aperture. Two range scales, one on either side of the oval aperture, are scribed on the upright member. One scale may be used as a range indicator to a known height target which fills the variable aperture while the other range scale is keyed to the trajectory of the projectile fired by the arm. If the variable length sighting aperture is used to fire the arm, the arrangement is such that a hit on the known size target is assured if a correct sight picture is formed using it in conjunction with a conventional front blade sight.