... This is for that back-up when things go bad (Rare and infrequent despite what people think about Alaska, but it does happen), but also for that spur of the moment chance at a medium range shot on moose bear sheep.
I was just re-reading the G&A 2003 Annual issue, which contains an article on the Gunsite Academy's "Back Country Wilderness Skills" which, the week the writer was there, was attended mostly by folks from Fish & Wildlife, US Geological Survey and Bureau of Land Management, and mostly from Alaska:
"Most of the riflemen in the group used one version or other of the big Marlin lever actions, invariably in 45-70... one of which had been customized by Wild West Guns.... Most of the rest were Remington 870's..."
No question that the .375 is a fine rifle and more than adequate for anything you'd encounter, but for your criteria, the 45-70 would seem to be a viable choice, esp. if you handload; otherwise Cor-Bon and Garrett make +P loadings.
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Stuart