I've used a Marlin 336 in .35 Remington w/200 gr Core-Lokts with great success. A .30-30 or .45-70 or .444 or .450 Marlin would all work very well.

Put any of those into the right spot & ya got a dead bear. Really, a .30-30 isn't a bad choice. Now ya just gotta sort out which load.
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"It's not that our liberal friends are wrong. It's just that they know so much that isn't so"