There is very little about primers in the public domain. Primers are not as simple as we think, and I don’t know all the little issues with them, but searches of DTIC documents show there are several ways to vary primer sensitivity.
I understand Federal makes a mil spec primer, it may not be available to the public, what I heard it has a thicker “harder” cup. A thicker cup, even with their more sensitive primer mix, would result in a less sensitive primer:
Finite Element Modeling of Primer Impact to Understand the Dynamics of Misfires
http://www.dtic.mil/ndia/2011ballistics/12080.pdf
What is in the primer mix can be varied to alter sensitivity.
I wish there was a book on primer making and all the different ways and techniques to make primers more sensitive, more consistent, dwell times, temperature sensitivity. But in the US, all that information is owned by commercial primer manufacturers and they are not telling anyone anything.