Very interesting thanks. Also interesting is according to this website, they mention that "US studies on the gun concluded it was overly complex and expensive by American engineering standards, so a version using fewer parts was developed (such as a new coilspring recoil system, instead of an hydraulic one, like on the Rheinmetall 120mm L44), and designated the 120mm M256 gun." I also vaguely remember looking at a picture on here that someone posted with a M256 gun taken apart and you can see the recoil system but I can't find it now.