I didn’t know SF was using DD uppers. He covers when he was in to modern, optics, etc.
Man I had no idea this guy is the same guy that wrote those articles.
Video was kind of iffy though. He got most of the stuff right but any gun nerd can scroll through Facebook and figure this stuff out so idk what the benefit really was, especially for the duration of the video.
Also I haven’t followed it in a while but the uppers aren’t full DD. I think the barrel is, maybe the gas block, but that’s it. There was A LOT of coverage on this back when it happened and in the ensuing few years.