As I've said, the force per square inch would be greater in the 28 gauge, but the total force would be the same....
....It's been fun.
Here's the kicker, you did not agree with this a few pages back when doc wonko made fun of the fact that more pounds could be shown to push on less square inches of a smaller bore to end up with the same velocity for the same weight of shot. I'm gonna call it weight rather than mass because I don't believe shot is fired in Newton's zero gravity vacuum.
Also, if you're conceding that some different force is acting on the shot that's closest to the PSI's of the ignited powder, doc wonko might turn on you and bite.
I also firmly believe that it takes more force to get an ounce of shot out of a 28 ga. tube than it does to get an ounce of the same shot out of a 12 ga. bore. To end up with the same velocity, I believe more friction needs to be overcome as the bore gets smaller, not just inertia. Fun in a weird kind of way.
