Most people buy a bolt rifle to shoot 308 ammo and a Marlin to shoot 45/70.
you got that right.
One thing they usually don't tell you at gun stores is that something like 90% of all actual killing of game animals in North America is inside of 100 yards. ASSUMING you're not trying to kill something 300 yards away, the 45/70 is vastly more lethal than any 30 caliber rifle including the ones with higher ballistics. The mildest 45/70 smokeless ammo available for a 45/70 will simply drop anything in North America and if you start loading the stuff up with 420 grain hardcast bullets, you can kill elephants and rhinos with it.