Thanks to Jim here, the confusion on the detent spring is a non-issue. I still cannot understand what the function for hole the middle of the tab or the material that was inside. Another photo online of the same style "D" buttstock had the same hole with the identical same material inside. I'm not concerned about it at this point as much as just curious.
The buttstock and pistol grip will get painted this week in the red.
Searching for an Edgwater Buffer last week produced one from Amherst Depot and apparently, I snagged the last one they had. They immediately shipped it out and it arrived in the mail already this morning. It looks very good.... except for wear around the edge of the buffer where the bolt carrier made contact. Other than that, it doesn't look bad at all...hoping to be as lucky to find a buffer tube next.
Dick