PALLADIN wrote:which Maximum do you consider ?
You've basically answered your own question there.
There is no universal maximum. It's what the operator deems safe.
For the purposes of the conversation lets say the 'maximum' the point there is a structural failure in any part of the rifle.
Two rifles chambered for the same cartridge could be built of different steels and having different strength properties. Quality/intelligence of design is a factor. Brute strength is a factor, e.g. thicker barrel/chamber, more/strong locking lugs, etc. etc.
You could have a brand new rifle build with modern precision and technologies, or a 100 year old one.
You could have a 100 year old rifle which has been maintained poorly, or maintained excellently.
Nick has tested the loads in his rifles and found them to be safe. You're shooting your rifles though, not his.
Power manufacturers are responsible (liable) for the data they publish. As a rule of thumb their data will be more conservative as they have to consider a broad spectrum of potential uses and safety is of much greater concern than bleeding edge performance.
The manuals are there to be followed. If you take it upon yourself to push the envelope that's on you, so be aware of the safety concerns and considerations and proceed accordingly.