I don't know about the 45-70 but when I was in Alaska I did a lot of hunting with a 444 Marlin and I used to carry a few 410 shells to pot a Spruce grouse or a Ptarmagin!
Had to feed them single shot! They worked pretty good, I never tried them over about 30 feet!
Don't bother saving the empties for reloading, they swell too much!
They worked for me!