I think you are missing the point that myself and a lot of other people are making, the type of bullet, the point of impact and the internals damaged on the way through are usually more important than the actual caliber used. A .223 with a good, modern tough bullet may drop a stag quicker than a .308 with a lighter more soft bullet intended for smaller game.
Put another way, if I'm out with a .223 and a decent stag walks in front of me do you think I'm going to unload and say nup? No, but am I going to be a lot more particular about my shot placement than if I had a bigger caliber? Yes. Am I going to take a pot shot at a piss-me-off stoat with a big magnum? No, for the other reason the round is just going to go through into and onward forever.
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