It depends on shot placement and distance. I don't see how the ethics nazis can proclaim a caliber is not ethical to use if it is legal. I don't see anything wrong with using a .223 or similar caliber if it's used within it's limits. I wouldn't try a shot with a .223 that I would with my .270. If you were hunting in the mountains and were facing a 400 yard shot I would prefer something more powerful than the .270. I would want something with ample power that would knock down a deer at a great distance. Remember just because you can type on a message board, that doesn't mean you can credibly declare someone who doesn't do it the way you do to be of unsound ethics.