I don't usually cruise the shotgun section, just killing time.
The JC Higgins M20 is also the High Standard M200, parts should be available from Numrich Gun Parts.
I've had mine for near 40 years and it's still reliable. It was my dad's before that. We have 5 or 6 of them in the family and only 1 has had any problems that I know of. We replaced the firing pin and trigger group of the same gun years apart. It is a plain barrel with rifle sights, used mainly for slugs, so it may have seen a bit more of heavy loads. My shotgun has a vent rib with changable chokes in a compensator. Other than some wear, it is the same gun my dad gave me long ago. If I were to go hunting tomorrow, I'd take that gun. I haven't modified it, so I don't know whose parts will interchange.
Fred