Introduced in the mid-1950s, the ZFK31/55 is a derivative of the K31 rifle configured for precision long range shooting that is complete with its matching 3.5X sniper scope. There were approximately 4,150 manufactured circa 1955-58 with many recently being imported into the United States. These rifles feature a straight pull K-31 type action with the chamber area marked with the standard Swiss Cross inside a Shield. It is fitted with a slightly heavier tapered barrel with a heavy reinforced blade front sight with integral flash hider/bayonet lug. The tangent rear sight marked 1-15 (100-1500 meters). This model has the integral scope mounting points with the 3.5 sniper scope attached. The top of the scope body is marked "Kern Aarau/V=3.5x75" over 4558. These rifles were all fitted with a beech hardwood stock and handguard with a checkered pistol grip area with a sheet metal buttplate. The stock has a front folding sheet metal bipod and a side mounted leather sling.