How wide would an action have to be to accomdate something up to 577? There is a guy on AR (screenname is "Colorado) that has built big-bore doubles on Stoeger actions with no problem. Though I am just in the planning stages of building my first double, I would have no problem using such an action and plan to. I have contacted several manufacturers inquiring about the pressures that their actions are proofed for and I've always gotten something along the lines of "we can't give out that information.". I believe that with the strength of modern steels and the strength built into modern actions due to the manufacturers' fear of lawsuits (meaning any built in the last quarter of the 20th century and newer) then any of them would probably work. Hence the absolute necessity to re-proof the newly built double.

Until we can get these manufacturers to stop letting lawyers dictate what information they can give us we can never be truly sure that any given action will stand up to the pressures of a DR cartridge.