With real black, especially Swiss, I have found that light to moderate pressure performed best with connies up to 300 grains. Over 300 I seemed to get best performance from a lighter seating pressure. With BH209 I have found that heavy seating pressure is pretty much necessary with all saboted rounds. I've not used it with any connies yet but I would suspect it would be the same. It's been so long since I shot PRB rounds I can barely remember the pressure but I seem to recall finding moderate pressure to be needed for good accuracy.