In March of 1943, while in the Santa Fe yard in Wellington, Kansas, Jack Delano spied this special load . . . a huge naval gun en-route to the west coast. I’ll speculate that this may be a 16-inch/50-caliber gun, the primary armament for the U.S. Navy’s newer battleships.
Note that three flatcars were required for transport, two carrying the gun, and the third for the barrel’s overhang. The blocking and bracing to secure the barrel looks pretty stout!