Saw this on two Erfurt frames and an accompanying VOPO Inspector stamp as well. This stamp is on the flat side of the frame and is in a sideways configuration (lazy...lazy.....lazy) Top one seems to be Crown over an Eagle (Constanzo WOL #
287) which is also 1950 East German People Military final proof, second one is crown over U which is similar to Mauser Commercial but I think this one is proof #161 (WOL) and represents 1950 East German Suhl Inpection proof???