By the way, I wouldn't consider the .270 Winchester a 300-yard elk cartridge, either.. But then, I have never been in a hunting situation where I couldn't stalk to within 200 yards of any animal, unless there was a canyon or big water in between us.
As I have said before, if you are good enough to shoot the heart at 300 yards, then it isn't much of a hunting challenge to shoot game at 300 yards. If you aren't good enough, then you need to realize you are too challenged to be taking those shots.
