Wworker,
From the pictures you supplied, I can surmise the following: Your gun is an Erfurt ( the Erfurt acceptance mark on parts), it has been buffed & reblued (thus the removal of the unit mark & blued rather than strawed TD lever and trigger), and the sideplate number is not original or has been restamped (it is too large to be an original stamp). The crown B is an acceptance mark.
