This isn't so much a question about the virtues of one over the other but in loading the former vs the latter. In theory, assuming a strong modern action without something weird going on, one would think a Rigby's load data would be essentially interchangeable with the Weatherby. Indeed, I've heard it said more than a little Rigby brass used to be made by simply turning the belts off the Weatherby. Before there is any great cacophony of "What's wrong with the Rigby at it's "classic" velocities?" the answer is "nothing". However, if more velocity can be safely gained while keeping (or who knows, even improving) accuracy what's the downside? (assuming recoil doesn't become overly objectionable)

First the obvious caveat; one should work up to the max loads even by Rigby standards. The idea of working up beyond that is, at it should be, a given. My question is are there specific reasons to avoid loading a Rigby towards Weatherby velocities? Possible issues being:

Is Rigby brass not manufactured to handle Weatherby pressure?

Could the Weatherby "freebore" be a big factor?

Any input appreciated for this decidedly "loonie" question.

If there's one thing I've become certain of it's that there's too much certainty in the world.