I don't use a 223 but looking at their web page, the 50 gr Nosler Ballistic Tip would be my choice. I use them in both my 22 mag(40 gr) and my 270 win(150 gr) and love them. http://www.ultramaxammunition.com/rifle.php
Every year many hunters and outdoorsman and women come out west from the midwest and east coast to hunt the prized mulies and elk. One topic that comes up often is altitude sickness. My advice for flatlanders is to get into the best possible shape. Start months before your hunt, usually really ramping up my cardio around March or April.
I run 5-10 miles 3 times a week, and also go for walks carrying my pack with about 50lbs to simulate what could be on my back. Another useful tip is to drink A...