Neither the action nor barrel flats have a date code.
A 1955 gun would have this Smokeless Proof mark
and the bore and chamber length within a lying Omega; a 1937 gun with a '
p' date code
I have been a bit confused by the bore over muzzle constriction mark, not usually found prior to 1910, which suggests the gun may have been reproved at some point.
Very similar barrel markings on this Von Lengerke & Detmold import which by the SN would be an 1899 DOM
https://www.icollector.com/Pre-War-F...tgun_i13827911