I just have to disagree with the prime choice being a problem for those who read what not to use. I have and have used a wide variety of standard primers and the only differences I have noted is some have a little blow back and some carbon up the flame channel a little more than others. I end up using win 209 because they eliminate the blow back with out any shimming.
Using the hottest primers like CCI Mag is not a very good substitute for decent breach plug design, especially since all it takes to modify them is a tiny bit of smarts and a drill and a tap.