Rocketman, you're still trying to make this whole thing unnecessarily complicated, except to engineers. Nobody--except engineers--gives a tinker's damn that the pressure behind the wad happens to be higher than in front of the wad. Obviously it's higher behind the wad than in front of the wad, so obviously it changes at location X when the wad passes. But that's both irrelevant and potentially confusing to shooters. What SHOOTERS want to know is: 1. Where does the peak pressure occur, and what is it? and 2. How quickly does that peak pressure decay? The pressure at a given point with which shooters are concerned is the pressure behind the wad. That's the ONLY pressure they're interested in at that point, and referring to it as "peak" or "maximum at that location" will only create confusion.
My wife, with advanced degrees in both English and journalism, spent several years as a webmaster and editor working with engineers. Her job was to take what they wrote and make sure it could be understood by non-engineers. Rocketman, if you're presenting a paper on the technical aspects of pressure within a shotgun barrel, you're doing just fine. But trying to present essential, useful information to everyone else . . . you ain't there yet.
All of this reminds me of the story about executions taking place during the French Revolution. Lawyer has his head under the guillotine, but the blade does not fall. The authorities determine it would be illegal to attempt to execute him again, so he goes free. Next is a priest. Blade does not fall. Authorities figure divine intervention, so he goes free. Next is an engineer, who looks up at the blade and says "Hey, I think I see your problem . . . " Moral of the story: Sometimes it's better not to present all of your technical knowledge.
