I believe the screw in the top rear of the action reveals it to be an improved Anson and Deeley invented by Emil Kerner. Axel Eichendorff's (kuduae's) comment:
"During the 1920s the Suhl gunmakers almost universally adopted E.Kerner's modification of the A&D lockwork. Kerner relocated the sears to the top/rear of the action. They turn on a screw located at the top rear of the action and engage a detent on the top of the tumblers, removed as far as possible from the hammer fulcrum. This arrangement vastly improved the leverage. As much less mainspring pressure rested on the sear detent, Kerner's top sears allow lighter and at the same time safer trigger releases. Secondary safety sears are unnecessary with Kerner's sear arrangement."
https://www.doublegunshop.com/forums/ubb...true#Post233792
