I am with LeFusil on my favorite configuration of Model 12s !
Something unique about the '97s is how short and compact the Receiver is.
I'm not as big a fan of the M1897 as I am the Model 12- But- i believe one reason for your observation of the somewhat shorter length of receiver on the M1897 as opposed to the Model 12- the external hammer and bolt design of the M97. And FYI- as soon as I get clearance from Dave W.- as this is NOT a doubnlegun item, I may be able to post a 1937 era M12 field grade plain barrel complete barrel and forearm assembly in the For Sale section-