You can obtain all of the information about your shotgun by ordering a research letter. Go to the menus on the LCSCA Home Page.
Members responding to these requests are trying to be helpful, but he responses are often in error. The published tables provide only the approximate date and may vary from the actual date by two or three years. Each of the serial number blocks was used up to five times resulting in more confusion. I've seen responses to the "when was my shotgun made" question be off by more than 40 years. A research letter is the only way to be sure when the shotgun was made.