H&R/Marlin are owned by Remington, have been for 4yrs now, I seriously doubt they'll have any info for you for that serial number, all of the serial numbers for their single shot firearms made since 1987 start with H, N, CA or CB, all earlier H&R (went out of business in 1986) single shot serial numbers made since 1940 have a prefix letter, if it has no letter prefix, it was made prior to 1940, see the year of mfr sticky above if it has a prefix letter you didn't provide. You're gonna have to post a pic more than likely, see how to post pics in one of the classified forum stickys.
Tim