The BCL102 Ambi one from SFRC needed some filing on the "ears" to fit the Stag 10. There was interference with the back of the receiver. Too bad it wasn't a clean fit. My grind marks don't look great thats for sure. It was kind of a bad area to do clean dremel work on the charging handle. If I wanted to grind the receiver itself I probably could have done a better job but this ones not mine...