From what I see, I would guess it to be a end of the War example, possible offered by Otto Reif, but more than likely made by Edgar Strempel. Either Otto Reif, Edgar Strempel or both had access or a store of Simson components that they used to fill orders. this one seems to be cobbled together from surplus parts and that might explain the odd Schilling forge mark on the water-table.

The chamber & cartridge length are present but few, if any actual official proofmarks. There are some very worn marks just forward of the breech with one be a W.

http://www.doublegunshop.com/forums/ubbthreads.php?ubb=showflat&Number=300183&page=1

Info on post WWII marks:

http://www.doublegunshop.com/forums/ubbthreads.php?ubb=showflat&Number=261946#Post261946

Cheers,

Raimey
rse