 The German government began the development of the Leopard 3 , although this was canceled after the fall of the Soviet Union . On 29 October 1991 , the governments of Switzerland , the Netherlands and Germany agreed to cooperate in the development of a modernization program for the Leopard 2 . Part of this program included the introduction of a longer 120 mm tank gun , a cheaper alternative to a brand new tank gun , increasing the maximum range of the gun by an estimated 1 @,@ 500 m ( 1 @,@ 600 yd ) . Although the gun is longer , allowing for a higher peak pressure from the propellant , the geometry remains the same , allowing the gun to fire the same ammunition as that fired from the shorter version . The longer barrel allows ammunition to attain higher velocities ; for example , with new kinetic energy penetrators ammunition can reach velocities of around 1 @,@ 800 m / s ( 5 @,@ 900 ft / s ) . The new barrel weighs 1 @,@ 347 kg ( 2 @,@ 970 lb ) . 
