I remember reading an extended article about that. IIRC, the deal was that while the BP actually has a higher spike it is just that, a spike and drops off much more quickly. Limiting the extreme pressures to the chamber area. Whereas the nitro loads have a lesser spike but retain more pressure further down the barrel where the walls are thinner. The reason why so many split over the hand grip.

I've also read the most of the problems with nitro blowing up barrels was when nitro was brand new people, being unfamiliar with the differences, would load the same volume of nitro as they did BP. The problem with doing that is obvious. lol

A few years ago DGJ did an extended multi part series of articles "Finding Out For Myself" where they took some damascus barreled guns and tried to blow them up by putting hotter and hotter loads in them til failure. I believe there were even a couple that they never could blow up. I think that's also where the data and charts explaining the different pressure curves was.