So, tell me again why we proof guns.
If I built a bridge for a one ton truck, and then drove a two ton truck over it just to 'prove' it would hold a one ton truck... and it sagged, but then came back to the original shape...
Haven't I just put more fatigue into the bridge structure than a million one ton trucks? Not necessarily!! Test loads (think "proof" pressure for guns) must be designed at appropriate levels for the material and the safety factor designed in. An airplane structure (application is very weight sensitive) might have a 1.4 safety factor where a bridge might have a safety factor of 3 or 4 (weight is of no consequence in application). Test loading above rated load would be quite different unless you were funded to run to fatigue limits. In the case of the bridge, that might be somewhere near infinity, OK, at least many, many millions of cycles. Since stress/strain characteristics are pretty well understood for metals, as is cyclic loading (fatigue), we can test a component to failure and walk away with a pretty good understanding of failure load, maximum working load, normal operating load, and the fatigue associated with each.Seems like all I've 'proved' is that it held a two ton truck once.
As a result I now have a well used instead of new bridge, that could fail from fatigue any time. No, not unless the load of double rated represented a fatigue life of one cycle. If the bridge is steel and no yielding of components occured (plastic deformation), then you have a many millions of cycles of fatigue life left.
On the other subject... three pilots sat there adding 'nose up' the whole time? If your attitude is +15, and your flight path is -15, take a wild guess as to the angle of attack...
I have to believe the fly-by-magic systems were preventing the crew from unstalling it. Like the Paris airshow... the airplane thinks it's smarter than the crew. Stalled for three minutes and no clue? I wouldn't accuse even Air France of that. Paniced people do unexplainable things.
A properly installed strain gauge on a decent test bed gun will give a reasonably accurate reading for pressure. Within the scope of quality control, other guns will experience a very similar pressure for this load. However, as Chuck has noted (several times), knowing the pressure of a load doesn't tell you about its suitability for use in any specific gun. You can use generically/anicadotially derived pressure limits for the gun. Or, you can calculate hoop stresses and set pressure limits that don't exceed the tensile strength of the barrel material.
