Mauser Hump revisited

[Thor]

This question comes up from time to time and is a key thing for new collectors to learn. Mauser Lugers have a hump or frame extension at the rear of the frame.
This was a frame extension at the rear of the frame just above the lanyard loop "staple". The purpose of extending the frame was better contain the rear toggle axle pin. In earlier DWM and Erfurt Lugers, if this pin was chipped or the frame stop at the front bottom of the receiver was worn the toggle/cannon assembly might move too far rearward during recoil and the pin could move sideways and jam the pistol. This design problem was fixed in another way with the Navy Luger pistol by changing the large end of this pin to a larger diameter better engaging the side of the frame ear at full recoil. Mauser begin extending their frames at the rear with a thickened back to better contain the pin. They later ground off the lower section back to the unextended length and this created double reverse curves that form the hump or bump. All 1937-1942 Mauser Lugers will have this hump, no 1936 or G dates have it and some K dates will have it and some will not. Shown below are two pictures that better illustrate this hump. One with the hump and one without it.
<a href="http://members.rennlist.com/lugerman/WithHump.JPG" target="_fullview"><img src="http://members.rennlist.com/lugerman/WithHump.JPG" width="400" alt="Click for fullsize image" /></a>
<a href="http://members.rennlist.com/lugerman/WithoutHump.JPG" target="_fullview"><img src="http://members.rennlist.com/lugerman/WithoutHump.JPG" width="400" alt="Click for fullsize image" /></a>