Its an H&R Model 120
A sidelock shotgun is exactly as it sounds. The locks are on the side of the stock instead of inside the action. A box lock has the hammer, sears, springs etc inside the action itself, side locks are primarily separate. They are attached to the action on the back and sides of it in the wood and the hammer, sears springs etc are contained therein. They can be detached without removing the action from the stock.
Marlin Model 59, 1959-1961
A bolt action Sears Roebuck shotgun would probably sell for $75 to $125 retail.
Sears Roebuck co.
The Model 14 was catloged in 1963 and 1964 http://www.histandard.info/PDF/Sears%20Shotguns.pdf
The JC Higgins 583.16 is a bolt-action 12ga shotgun made for Sears by High Standard in 1948/1949.
your shotgun was made by Sears & Roebuck /High Standard in 1949 .Sears owned High Standard back then in good shape its worth about 100 dollars your shotgun was made by Sears & Roebuck /High Standard in 1949 .Sears owned High Standard back then in good shape its worth about 100 dollars