The beauty of the 45-70 is that high velocity and recoil is not necessary to be an effective killing machine. Any velocity from 1200 to 1600 fps is very adequate. My two favorite loads are simple-40 grains of RL7 and a 405 grain cast(mine) bullet. Or just fill the case up with BP and lop off the excess with a butter knife, and seat the bullet.
At 1600 fps with a 405 grain pill, the only thingthat restricts your"killing range", is your ability to shoot your rifle. 200 yards is a piece of cake. All you need to do is practice. If you are willing to practice then the 45-70 is the greatest round there is. If you are not willing to practice, then stay away from it. It is really that simple.
Buy500 inexpensive cast bullet's and shoot away.405 grain lead pill's of just about any make up will be effectice on deer or most any other game short of dangerous game. Tom.