You are probably pretty close to the truth.
Of course is it possible to stress the material until its broken but what probably happends with the firingpin that cracks (I have NEVER seen one) is that they are hardend tohard and will prabably crack anyway.
I haven't cracked any of my firing pins after extensive dryfirng.
Regards HÃ?Â¥kan
http://www.vapensmedjan.com