This is a 14.33 minute video on how to identify forge marks on the upper and lower receiver. Maybe I am just fascinated with the research this guy has done uncovering all this or maybe I am just a geek. Anyway, this video will help you identify exactly who forged and finished your upper and lower and in any combination of companies. Mine is a Cardinal Forge upper and a Cerro Forge lower.



https://www.youtube.com/watch?v=SQcRY7ELcMQ