If a single powder and projectile mainly for subsonic hundreds seems to work for .300 Blackout that will be good. If it turned out to that CFE 223 could fill that role that may be the On top of that worlds. Keep on with published details only, the sole exception https://300blackoutreloading42840.shotblogs.com/5-simple-statements-about-300-blackout-reloading-explained-52919808