 By 1990 , the L / 44 was not considered powerful enough to deal with the future Soviet armour , which stimulated an effort by Rheinmetall to develop a better main armament . This first revolved around a 140 @-@ millimetre ( 5 @.@ 5 in ) tank gun named Neue <unk> 140 ( " new tank gun 140 " ) , but later turned into a compromise which led to the development of an advanced 120 mm gun , the L / 55 , based on the same internal geometry as the L / 44 and installed in the same breech and mount . The L / 55 is 1 @.@ 3 metres ( 4 @.@ 3 ft ) longer , giving an increased muzzle velocity to ammunition fired through it . As the L / 55 retains the same barrel geometry , it can fire the same ammunition as the L / 44 . 
