Did you research the Young Manufacturing bolt by chance?
One of the best youtubers I watch (IMO) did a lot of 7.62 ARs and his solution ultimately was the YM bolt.
I highly recommend his channel for the reviews in general. He's the only guy I've ever actually supported financially on patreon/subscribe star. He helped me with a build and is building an upper for me right now actually.
Added video to watch list.