Natman I'll submit for your consideration that with todays technology, there is absolutely no reason for anyone with any firearm to take a shot at an "unknown" distance, save for maybe someone still hunting timber. Any hunter that wants to be thoroughly ethical will be carrying and using a range finder.
A good point, let me clarify. I meant "unknown" in the sense that it's not a premeasured distance where the hunter knows in advance exactly what the range is. Even with a range finder a tiny percentage of error in distance estimation / holdover will produce a miss with as much drop as a 45-70 has.
The wind is a big factor as well, and I've watched many atime as a licensed professional hunter herder, when a clients bullet went zipping well past an animals backside because the shooter didn't factor in the wind with his belted magnum...
Agreed, and given the long flight time of a 45-70 the wind has much more effect.