Yes, the action and barrel are certainly made between 1918 and 1945. The action may even be older, of WW1 military production or of commercial Mauser, Oberndorf make. Disassemble the rifle and post photos of all the proofmarks under the barrel and of all marks and numbers under the receiver ring. If proofed post-1923, a date of proof, month and year, was likely marked too. Imho the rifle left the Krieghoff shop as a model „Gibeon“. Double set triggers were standard on the Gibeon. The model Buffalo only was offered with a single trigger too. More recently the rifle was restocked to a 1970s „British“ syle. The out of fashion flat bolt handle was cut off and a modern one welded on.
As Krieghoff was a major military arms maker during WW2, The occupying American and later Soviet forces „liberated“ all production files in 1945. So any production numbers may be buried somewhere in an American or Russian archive, unavailble for research.