If one powder and projectile principally for subsonic loads seems to work for .three hundred Blackout that would be great. If it turned out to that CFE 223 could fill that role that might be the best of all worlds. The 5.56 NATO origin Tale operates throughout the turbulent sixties https://300blackoutcases07407.wizzardsblog.com/39038377/top-latest-five-300-aac-reloading-urban-news