I would just like to say that it's not the gun it's the person like elknut1 said. It depends on the shot placement. I have killed elk with both a 30-30 and a 300 savage at up to two hundred yards. This was because I felt comfortable with the shot and knew that I could hit the mark. My brother-in-law shoots a 243 and is very acurate with it. I have seen him take a nice six point down at 250 yards with two shots. One was right behind the front shoulder and one in the neck. The elk didn't go 3 steps. It's the person and the confidence they have in there gun. If someone can take a bow and arrow out there and take the same elk I think a high power rifle should be able to do the trick. Practice and more practice with whatever you are going to take out in the woods and know that you are going to take an ethical shot.
BowElkDwn