Not very long ago someone posted a chart that showed the difference in PSI between primers. If I recall it was not a whole lot of difference between regular and Mag. Now if that has anything to due with ignition, I don't know.
If you look at Hodgdons data online, they use a Mag primer for everything in a Mag cartridge. I asked them about this and they stated it was just to keep everything consistent. For example they use a Mag primer when loading 357 with HP 38.
Why is 2400 a non mag primer and H110 is? Way are Win Large pistol Primers OK for regular and Mag and CCI's are not? I wonder if these Wolf Primers I use are hot enough?
Oh so many variables.