Good overview, nice to see people actually doing their research. Balanced recoil system is a simple, yet amazing concept, and recently I tried to document the history of civilian Saiga 107 - mostly what I saw myself in the last few years: https://www.thefirearmblog.com/blog/2018/06/11/balanced-recoil-sporting-rifles-a-brief-history-sr-1-saiga-107-ak15/