Pre 855,000 guns should have serial number on front of receiver and on the barrel as they were hand fitted. don't know when the corn cob forend started or ended. I have a 16 gauge with a 229k series serial number and a 20 gauge from early '70s production.
Thanks. This one had the serial
# on the barrel only, and having learned it is most likely post-war, could very well have been the original receiver. It was in great shape and so was the wood.