After I started this thread, I decided to email CCI and ask them directly about the pressure of their CB rounds. I was hoping for a specific answer. I got a useful answer, but not at all specific. Linda Olin of their techical section in Lewiston Idaho gave this response:
"The CCI CB shorts do not actually run anywhere near the SAAMI maximum of 21,000 psi. None of our CCI short products 'exceed' that number on average pressure."