Ted;
I think where we do not seem to be communicating is you are speaking "ONLY" of max chamber" pressure. I am speaking of the total pressure from the time of ignition of the powder until the charge exits the barrel. If you push the same weight charge out the barrel at the same velocity then the "Total" pressure is going to be virtually identical, matters not if its shot by a 90 lb petite woman or a 300 lb fat slob. "IF" you suspended the gun from wires or something so it could have "Free" recoil then you would never crack a stock, regardless of load.
As the gun is bolted shut & is with the exception of the movable charge a closed cell pressure chamber I do not see these external factors having any effect on the frame stress.
To go a bit further with my load analogy & remember this is from & old guide, I am not recommending any of these loads. Again 2 3/4" WWAA hulls & WW 209 primers
Load 1 - 17.5 grains Bullseye; WWAA12 wad; 1 oz shot,; 1200 fps @ 9,900 psi
Load #2 - 23.5 grains Herco; WWAAF114 wad; 1Ľ oz shot; 1220 fps @ 9,900 psi.
Here we have a 25% heavier shot load, approx 2% higher velocity & a 34% heavier powder weight. @ identical "Pressure. I do not know what the difference in the weight of the wads is, but that will not offset the other factors.
Two things I will Guarantee you, 1 The "Total pressure to get load #2 out the barrel is Higher than load #1, in spite of having the same Max reading. 2 if either of them flexs a gun frame beyond its yield point it will be #2,
You might somewhat compare this with running a Marathon. The one who wins is the one with the fastest average for the entire race.
a loser way back in the line may have had one Burst of speed that was faster than any the winner accomplished, but he didn't maintain it long enough to accomplish the win.
