Thanks for the information. I just today received a 311 made for Sears under the JC Higgins name. I took it apart and found a "D" in the circle on the inside of the receiver and the underside of the chamber end of the barrels.
If I understood your post correctly, that would make this shotgun a 1952 model?
Nope, the date code will be a letter and number, inside a circle, stamped on the outside of the receiver. I have a 16 gauge 311A made in 1949. It has an American walnut stock and forend {original equipment on early production 311A's} and the date code is stamped on the bottom of the receiver just ahead of the trigger guard.
