As I stated before, I'm sure it is capable in the right hands.
Just because someone who is dedicated and practiced is able to make long shots, does not a good long range caliber make..
He is able to overcome the deficiencies of the cartridge thru skill and practice. Also, He's using a target rifle, not a Marlin Lever gun sighted in at 100 or 200 yds.
As along range hunting caliber, there are much better choices.
Shooting at extreme ranges with a Marlin Guide gun in 45-70 is a risky proposition at best and beyond the capabilities of most of us who hunt.
As far as gut shooting Bison, you may be right. Gut shoot a Whitetail or Elk and he's gonna run and those are the animals people are discussing here.
JM.