Ultimate yield strength, when considering the strength of a revolver, is actually the ultimate TENSILE strength of the material across the thinnest portion of the cylinder - the chamber wall over the locking notches.
Ultimate tensile strength is the maximum pulling force which the part can resist without breaking. The chamber pressure effectively stretches the chamber wall, pulling it apart. Yield strength is effectively a resistance to a singular stress event, without permanent deformation, or without failure in the case of Ultimate yield strength.
What you are referring to - a resistance to repetitive strain - is elasticity/resiliency. The modulus of elasticity is what dominates here. The two are related, obviously, but very different in and of themselves. In this way, since the metallurgy and heat treat on the Redhawk's and Super Blackhawks are similar enough to class as the same, higher pressure loads will deform, without failing, the Blackhawk or Super Blackhawk before a red or super red. Similarly, since the yield strength is higher, there will be less net proportionate stress for the same old level, so the Redhawk will sustain longer life of "hot but not destructive" rounds before the strain dislocations finally overcome its elasticity.
Again, knowing the metallurgy and the dimensional design of both, the Redhawk/Super Redhawk has the greater ultimate yield strength.
That's not to say the crane won't warp nor the basepin gall and the MECHANISM of the Red's not start failing before the cylinder does for either model in that case of "hot but not destructive loads." I've shot S&W revolvers loose - including the legendary 629, but I have yet to do so with a Ruger. In the event of wearing, replacing the mechanical parts of the Single Actions will be much cheaper than doing so for the Double Actions. In the case of sustained use, the single actions - assuming proper heat treat of the basepin - will stay tight long after a DA has started failing to lock up. Equally, when the Blackhawk does start wobbling, a $20 basepin will rectify the problem, or a $7 hand, a $10 locking bolt, and a $100 take off cylinder (or a trip back to the mothership for all of the above). For the DA, most likely you'll spend $150 on a crane and cylinder, $10 for a cylinder stop, and $7 for a hand - all in take off parts. Send it back to Ruger and these days you're more apt to get a replacement than a repair when you start talking crane and extractor replacement. Just cheaper for them to write off the warranty replacement than fit new parts when it gets that bad.
But again - my statement regarding ultimate yield strength of the two is accurate.
