wapitiman:
Please don't think I'm putting forward some unfounded bias here. I have hunted buffalo with both action types, and while I still love to hunt with my ULH Alex Henry .577 double, and wouldn't part with it for anything, I can clearly appreciate why such rifles are now obsolete in the face of the top-lever hammerless gun.

If nostalgia is your thing (...and its often a big part of mine!), then hunt DG with ULH doubles by all means: I wish you well. I simply fail to understand your obvious need to justify such action on the grounds of strength/efficiency/safety.

..and BTW, there are plenty of Jones-patent underlever hammerless doubles out there, and most use rods to cock on the fall of the barrels. Alexander Henry built stacks of them, even though this practice "hollows out what was once a strong action"! Guess what? They're still strong actions! ...just like top-lever doubles!