Hmmm...I always thought the Mark V was THE strongest action, with those nine locking lugs. Least that's what they bragged for years. Metallurgical problems? Sure would be interesting to see the parts, although I suspect several lawyers are guarding them.
The Remmy 700/721/722/725 have always been considered stronger than the Mk 5. The strongest non-custom action is supposedly the forged Japanese Arisaka.
However, on ANY modern bolt rifle the barrel is supposed to bulge/burst before the action gives. IIRC, I think barrels are designed to fail around 135,000 PSI and actions around 200,000 PSI.
Of course, if there is an obstruction just forward of the bolt, then you're in trouble no matter what you shoot.
