There are some published serial number lists.
this shotgun was made by Harrington & Richardson and is there model 120.www.e-gunparts.com sells some parts for this gun. searching under Harrington & Richardson model 120 will yield more results for you. good luck.
Blue Book of Gun Values
Made through the late 1940's - mid 1950's. Value under $100.
I find no Harrington & Richardson S/S shotgun manufactured since 1885.
Try Gun Parts Corp
The Harrington & Richardson 349 Gamester shotgun does not use a clip. It has a tube type magazine that is a pemanent part of the gun, loaded by sliding shells in from the bittom of the gun.
about 80 bucks. I have seen them go for 130, and have seen them go for 2 for 50. Just gotta find the right person.
Ypu might try Numrich gum parts. They have the largest inventory around..Try gunpartscorp.com. Maybe they can help.
Unlikely that detailed sn data has been published.
Bill Goforth has an excellent book on the H&R shotguns. You can do an internet search to find a copy.
Please list all the markings on the shotgun. Harrington & Richardson were producing hammerLESS double shotguns as far back as 1882. sales@countrygunsmith.net
TRY THE BLUE BOOK OF GUN VALUES FOR PRICES..