The Weatherby Mark 5 and Champlin are the two strongest actions I have ever read about.
The Lazzeroni Sp. ? is one of the strongest modern actions.
The Weatherby has withstood chamber pressures close to 200,000 psi
I couldn't care less really as I prefer a claw extractor to a strong action with a puny extractor like the Remington. JMO
Sag.