Greg:
At the time of their inception, break-open double rifles were not as strong as Mauser-style bolt-rifles. Accordingly, nitro-express chamberings turned up little more than 17 or 18 tons max working pressure. At the time, Mauser rifles were quite content with cartridges generating well over 20 tons, up to 25 tons or so.
Modern double rifle design and better quality steel (and more consistent manufacturing standards) mean that today's double rifle is a far stronger action than those of 100 years ago. As a result, many European and a couple of American makers are happy to chamber just about any cartridge you like!
In a destruction test, I'm sure the double would fail before a modern bolt-action, but you never know.... !
That's my take on things, other opinions..?
