Nonsense..
The 45/70 is quite suitable for grizzly or Alaskan brown..
The only precaution I would consider is using the commonly available "light" loads..
( I wouldn't have one (a rifle) that couldn't handle a full load...)
Comparably, it would be (nearly) as effective as a .50 cal sniper rifle.
Talk about 1870 technology, remember that the 45/70 was used to kill BISON..
And that the .50 cal rifle is ALSO 1870 technology.. developed for the same purpose..
Okay, tell Jimmy hello.
You're correct about the 45/70. With the changes in powder and projectiles, it's not your grandaddy's rifle anymore.
I think you're a little confused by the .50 though. The modern .50 caliber sniper rifle is far and away more powerful than anything they had in the 1800's. Today's .50 is a .50BMG caliber. It stands for Browning Machine gun. The cartridge is the same which is still used in the M2 machine gun.
The Standard load in the Civil War was a muzzle loaded .58 caliber Minie bullet with about 70 grains of blackpowder.
After the Civil War, the 50-70 cartridge was accepted followed by the 45-70 during the 1870's.