"It is a common misconception..." JB, I must disagree that near peak pressure the rate of change of volume is insignificant. QL is predicting that at peak pressure, the bullet is already up to 1000 fps. That is 12 inches per msec which works out to an increase in volume of about triple the case capacity of the .30-06 every msec. The pressures in the RSI trace are above 90% of the peak for the .25 msec or so centered about the peak, so the volume increase is about 3/4 of a case during that time. This rate of volume increase coupled with decreased grain size remaining seems perfectly consistent with QL's figuring that the burn simply can't keep up with the bullet.
You ask why does the curve drop off so quickly, yet I ask why doesn't it drop more quickly. My claim is that if the powder were fully burned by peak, then the curve should fall off more sharply. Instead, we see a big dome that's roughly centered around the pressure peak.
As for a 60 ksi trace, had I one at hand, I'd be happy to look it over. That one on their web site was the first I came across. I'll see if I can't find one on their site tomorrow. I'm heading out for the evening.
