Note that there may be some leeway in a Luger spring, BUT the rear toggle link has a protrusion that hits the frame for the final stop. Elsewhere in this blog it talks about the rear toggle getting cracked, as a part that wears out. I suspect there is a connection as there is no final soft rubber buffer if the toggle reaches the end in a hard recoil.
http://forum.lugerforum.com/showthread.php?t=6491