Your best bet would be to visit the site of Numrich Gun Parts Corp.If it is out there,they would have it.They may be found on the web.
The Savage 820 model is an older gun that was made long before the current accessories. No one ever made any after-market accessories for this model, it is not noted the year of manufacture.
I beilieve 1952-1953.
You will probably have to have them made.
Mossberg made parts only.
There are some sources for Crescent shotgun parts, but it is very possible that parts will have to be repaired/made.
High Stadnard made the shotgun. Some parts are the same as the Higgins model 66. and a few parts are the same of the later High Stadnard Supermatic shotgun models See the parts lists at www.histandard.info
DO NOT ATTEMPT TO USE PARTS THAT WERE NOT MADE FOR YOUR WEAPON!!!!!!!!!!! Danger, danger, danger.
1954
Your Stevens Model 820B in 80% condition would probably fetch $80.00 to $100.00 at the right time. Most of the Stevens 22 calibers and shotguns were considered utility guns and do not hold a great attraction for the serious collector. They are a fine product with a long and proud history. Hang on to your J. Stevens Arms and Tool Co. firearms. They will serve you well and when they need repairs the parts are available widely and at very reasonable cost.
The answer to your question is Yes! 16gauge shotguns and shotshells are still made.
try numrich gun parts
Ruger made a Deerfield rifle, Ithaca made a Deerslayer shotgun. Nobel made the Deerfield shotgun line until 1971. Very few parts available and what is available is through Numrich. Value would be something like 175 in very good condition due to the parts problem.