I have seen such poor performence with a hot loaded 45-70 with hard cast and Nosler, Hornadys that I am pretty sour on it..I have a number of filmed kills with it and it would make you sick to watch..I even lost a Guide Company because the guide/owner insisted on a one shot kill and we followed a lung shot bull for a half mile waiting on him to die and he wouldn't let the hunter finish him off..I got mad and shot the bull and walked to my truck and went home..I have that one on film.
I used the 45-90 a bit on elk some years ago and it was better when loaded properly, but again I am not impressed with any of those big slow bullets...If I were to use the 45-70 today it would be in a Ruger no. 1 and I would load it to 2000 plus FPS in that strong action, but why, when I can get the same gun in a .458 Win.
Just my opinnion based on my experience with the caliber, but I believe many 45-70 owners have not used the caliber much and just want to believe its effective out of nostalgia, others have apparantly had better luck than I...but thats why we have so many caliber choices, because we all have a right to an opinnion.
