I don't know what that is - it was one of the questions I hoped would be answered. How does a case extraction ring work?
Also, you'll notice a little chunk of wood missing behind the safety. It appears to have been partly covered with epoxy. I may try to repair this myself (carefully) with a walnut scrap.
It looks like someone bedded the barrel as there are little bits of epoxy visible in places. I haven't taken the rifle apart yet.