I don't know that I could add to anything already said. My grandfather killed quite a few moose and caribou with a .30-.30. I've killled one elk with one as well, as well as one with a .308, and a dozen or so with the .06. I've seen plenty of elk killed with .270s and a few with the .25-.06. Shot placement and effective range for the particular cartridge, I think, are key. I expect it is far more important that you have a firearm that you are comfortable with, enjoy shooting, and can shoot with confidence, than the particular caliber. My .06s kick pretty good, but don't bother me. I shot a 300 mag once that had relatively little kick to me, and a .30-.30 that had a whale of a wallop!As has been said before, the kick is based on a lot more factors than the caliber. I wouldn't have a qualm about shooting the animals you listed with a .270 or any of the .30 calibers. Regardless of what we shoot, we need place the shot well, and always follow through when the animal doesn't drop. I don't believe there is a caliber that will always drop an animal on the spot unless the central nervous system has been hit. Most of the time, maybe, but not always. Some elk go right down with a single shot through the lungs with the .270. I shot one bull that took two through both lungs (which also shattered the shoulder on the off side), with the .06, and still ran a good 75 yards before going down. He went down out of site and tracking was still necessary. Every other elk I've killed with an .06 went down within a few yards of the shot, with one shot.