Yes the full explanation is much closer to actual facts. The main point I would still disagree with is that total combustion of the powder charge has been reached at the point of max pressure. While the above graph is based on time rather than distance the curves are very similar to those whch have been shown related to distance. In fact as best I recall I was the first one to mention these pressure curve graphs & lacking a photo program at the time scanned in a copy of the duPont one made in the 1920 with Black, Dupont Bulk Shotgun, Infallible & DuPont Oval as I recall which I sent to someone to post for me. This graph has surfaced many times since.
"IF" that ratio of twice the volume = half the pressure were always the case then the load giving the lowest max pressure woulds "Always" give the lowest velocity. I think we all understand this is not the case.
The "Fly in the Ointment" here is that the P:V ratio is not an exact constant & varies with the burning rate of the powder. As can be seen in the curves the slower powders continue to release more gases (Still Burning) for a bit longer past the point of max pressure than do the faster ones, though all do so to some extent.
