If you stick with black powder or black powder safe loads, I would think your safe with most anything. I would also send them out to get case hardened also, as it will add some more strength to it. I know they put some heafty calibers in them back in the day, not sure what the upper limit is though, it's a pressure thing, as much as a size thing, so a 50-140 with a 400gr bullet is less pressure then a 50-140 with a 700gr bullet. The 45 case will have less bolt thrust then the fifty call case etc. I know they built 45-120s on them, but not sure how long they lasted though. If your going for a big Boomer, I would also have the person doing the case hardening, to add kasinite to the locking points, as it adds more carbon and a little deeper then just regular case hardening does. These were pretty common for Buffalo and meat hunters to use. I can't remember off the top of my head, what their pressure limit is, but you could Call C Sharp's or MVA and talk to them about it. Remember, their is a difference between what you can do and what you should do.
