Based on my readings in R. Gibson's "The Krieghoff Parabellum" on page 40; the straight edged knob on the locking bolt (i.e. take down lever) is typically a Krieighoff characteristic...is it not ???
The other luger manufacturers (DWM, Mauser, Simson) apparently used chamfered or stepped edges on the knob... <img src="graemlins/yltype.gif" border="0" alt="[typing]" />