"Ethical kills" is somewhat misleading , because the shooter has far more to do with that catch phrase than the cartridge or caliber used.
I have killed a number of animals at distances many automatically dismissed as " unethical" for any number of reasons, from too small a caliber to too far. The fact remains that none of people admonishing me for it had ever done it before, or even shot that far on targets ( or at least hit the targets) and where I was hunting , I had been practicing on the same river breaks for the whole year as well.
The wind , TOF, and visibility along with the shooter's ability to call those conditions has far more to do with it.
I have passed far more shots at long range than I have tripped the trigger on because of of the weather conditions.
At the same time, I am not one who tries to make a somewhat obstructed 50 yard shot because I have a " brush buster" cartridge either, which is very common , from what many hunters tell me they do.
Cat