I'm not sure I understand what you're asking. Anything called 20 gauge is a shotgun. A bolt action gun is one where each time you fire it, you must lift the bolt handle and pull back the bolt to eject the shell, then push it back to insert another shell. The two cannot be synonymous.
Click on the Related Link to see an image of a Mossberg Model 185K.
1928
looking for parts
500
Mossberg
The Mossberg model 185D bolt action shotgun was made from 1947-1959.
$20 to $150 depending on who wants it. Bolt action 20 ga shotguns are not highly prized.
Go to Cheaperthandirt.com
50-160 USD
Mossberg, it is their M#85 ( I'm assuming that this is a bolt action shotgun).
Assuming you mean the Stevens Model 238 bolt-action, I have magazines. sales@countrygunsmith.net
what is a J C Higgins Model 583.9 20 gauge worth
20-140 usd