WW did not use FIFO on commercial models, as might be stipulated in military contracts. With just about any model can see a barrel older than receiver SN indicates. Mostly pretty close, but with transition/late prewar years sales were slow. Could easily see prewar bbls (and metal finish, some models) on postwar receivers, etc.
Curious. Has anyone ever seen 20lpi checkering on a honest original postwar? Any model? I have not.
What should give pause are barrels of later date than the receivers suggest. And yes, the WW reinvention industry worked well for the M-70-savvy. I saw how it was done, including a matched pair of 9x57s. Made up in the '80s, but if you can't prove it....
