If it is a J.C. Higgins bolt action shotgun, there is a small set screw on the left side of the receiver top between the bolt handle and the ejection port. Use a flat tip screwdriver and take out that screw. It is litterally the metal peg that the bolt is running back into. Without the screw, the bolt comes straight out the rear.
Stevens
http://www.histandard.info/PDF/Sears%20Shotguns.pdf
The Sears Ranger 105-20 16 gauge shotgun came out in the 1930s. The Sears Ranger shotgun has a 26-inch barrel.
Sears Roebuck co.
The Sears 16 gauge model 101.40B shotgun was manufactured between 1955 and 1968. This model was produced by the Stevens division of the Savage Arms Company and was sold under the Sears brand. It is a bolt-action shotgun, which was popular during that time for small game hunting.
Depends on model and condition. Typically $100-$150.
No age records, most likely a Mossberg shotgun, values $50-$75.
http://www.histandard.info/manuals/sears/bashotguns/index.html
The JC Higgins 583.16 is a bolt-action 12ga shotgun made for Sears by High Standard in 1948/1949.
http://www.histandard.info/PDF/Sears%20Shotguns.pdf
about $100
I believe that your Sears shotgun is a Winchester model 37A shotgun that was made for Sears Roebuck And Co,.