Larry;
First & Foremost you have to "Understand" what you read & Cite. Yes, the pressures quoted are an "Average" of Max peak pressures. I apparently wrongly;y ASS-U-MEd that everyone here understood that.
All pressures unless one is only talking of a single shot are averages.
I specifically Stated I was NOT speaking of peak pressure, BUT of the total pressure for the length of the barrel, which is also an average when a number of shots are fired. The Clue there in what you posted is the WORD MAX, which again, I Specifically stated was not what I was speaking of.

What part of that is Beyond your Comprehension, Do Tell, & I will type real Slow & try once more to explain so maybe you can read it well enough to Comprehend.

Miller/TN
I Didn't Say Everything I Said, Yogi Berra