Hard data on this variant is limited, but according to legend during the Israeli War of Independence an order was placed for 200 marksman variant K31 rifles, evenly split between rifles fitted with diopter iron sights (known as the FK31) and rifles with Kahles 4x scopes (the ZK31 variant), to be delivered via clandestine means due to arms import embargoes then in effect. Reportedly, Hammerli made the rifles on the pretense of fulfilling a Nicaraguan contract, loaded them on a transport ship that then went down somewhere off the coast of Egypt, and later identical rifles were seen in the hands of IDF snipers. This specific rifle later passed through the proof house at Birmingham and later through the importer Woodcock Hill, the former adding their marks to the left side of the receiver and underside of the barrel, the latter using the underside of the barrel and left side of the rear sight base. Blade front and tangent rear sights, with no Swiss military markings on the receiver exterior, straight pull stock, and a leather sling. A pair of bolts have been added to the left side of the receiver to act as the mounting points for the scope, with appropriate cuts made for the mount in the wood. The base is numbered to match the receiver on the exterior, with Israeli nomenclature on the underside, windage adjustment integrated into the rear sight, leather lens caps, and "K. Kahles/Wien/H/4x60" marked scope.