I think the stories about SB actions being softer steel are urban legend. No personal experience with them, but I've never seen documentation of a failure from inferior metallurgy. Posters on other forums have checked rockwell hardness and they seem to check out.
I think the limiting factor here is the action design is from 1898 and intended to be used with rounds in the 7x57 pressure range. Sure, they've fit bigger rounds in them safely, but if I were building high-pressure magnum from the ground up, I'd pick something else.
I don't care for Santa Barbara actions because they were made in Spain and I don't have enough faith in Spanish manufacturing quality to spend money and time building on any Spanish action, commercial or military. I don't really care for Yugoslav Zastavas either, but the ones imported by Interarms seem to be of higher quality, at least better fit and finish, than the current ones. That is my take on them and since we all have different life experiences, opinion and actual outcomes will necessarily be different.
