I saw that too, and of course old Researcher saved pictures!! It appears to me that the 079 is stamped over 257.
242079 06 XK3 X = Dec. K = 1941.jpg
The barrel flat has a repair coded XK3 X = December K = 1941. Two things that caught my attention was not a production date code present and no choke markings I'd expect at that late date.
241968 01 26-inch, 16-gauge, XJ X = December, J = 1940.jpg