The steel is supposed to be better than the originals, but the frame lacks the reenforced side rails that were designed to limit frame stretching. MGM lists some cartridges for the G2, but not the originals. Perhaps they will update their list for the SSKs, perhaps not. Personally, if a combination is borderline, I'd lean towards an Encore frame.
Then, there's also recoil to consider. Good examples are the .444 and .45/70, which are safe in all contenders IIRC, but might be more fun than many would want to have. I kinda wanted a MGM .444 barrel, but theirs requires a special (ML) forend to handle the recoil, so I bought a regular .44.
