Here is an update to this peculiar attempt to convert a standard Luger upper assembly to .22 Long Rifle.
As I continue to study the modifications made by the original engineering gunsmith for this .22 coversion attempt I am awed by his ingenuity... and left scratching my head by other things...
This image shows extensive modifications to the toggle to include a complete change to the design of the sear/striker/disconnector/toggle linkage:
Point D arrow is pointing at the new Sear/Striker. The sear engagement point is at Point A. The sear has been made an integral part of the breechblock. The firing pin release surface is completely different to match the new sear and the firing pin retainer is held in place by the pin at point B.
The new sear bar is pinned in place at point C and works much like the original sear does on the upper receiver.
The new disconnector shown at point H is identical in operation to the original sear/disconnector engineering except the whole operation has been moved to the breechblock.
Notice that the forward toggle cam is behind the new sear bar at Point G.
Point E and Point F show changes in the geometry of the toggle pin points to allow blowback of the breechblock without movement of the upper receiver. This is the reason for the new sear/disconnector. Without movement of the upper receiver the old sear/disconnector would never disconnect.
The original sear bar has been modified by replacing the spring loaded disconnector pin with a solid non moving pin that has a protrusion that passes the movement on to the new sear bar.
I will make more and better photos of this engineering and update this thread as I find time to disassemble the toggle further.
I still haven't quite figured out the purpose of the spring loaded pin behind the open toggle joint, as it does not engage anything. Perhaps it is a helper to opening the toggle on firing.
More to come as it happens. I hope all you armament engineering enthusiasts are enjoying this reverse engineering investigation thread.
