Up till WWII, I'm leaning toward the possibility that the Germans sourced some of the sidelock components from their Belgian counterparts. Post WWII, it would seem that most were home grown.

http://www.doublegunshop.com/forums/ubbt...true#Post229383
Mainwaring thread

http://www.doublegunshop.com/forums/ubbthreads.php?ubb=showflat&Number=176769&page=1
Jules Bury type locks/examples

http://www.doublegunshop.com/forums/ubbthreads.php?ubb=showflat&Number=202510&page=1
H. Barella peddled example - sourced


Kind Regards,

Raimey
rse