You might also just leave it alone
Some people view a carbine as a bunch of parts, others look at it as a living unit that had a history and a story. The price is fine and as a shooter example it is what 90% of carbines look like (except for the blue sky stamp). As I said, some people look at these things as a pile of parts and immediately want to break them up. I have a NPM that I bought as a shooter from CMP. It has some parts that are valuable like a Rockola hammer. I just shoot it and enjoy it. I have no interest in solving some mysterious puzzle that I don't really have an answer for. It is what it is and did what it did, I wouldn't want to destroy that karma to solve a puzzle.