I am going to purchase parts for a lightweight custom hunting rifle based on a trued 700 long action. I am having a bit of trouble picking a cartridge. I do reload so its not a huge issue to do my own ammo. I also know that all of these are commercially available; some more than others. I have it narrowed down to: 6.5x284 .264 win mag .270 .280 AI 7mm Rem mag. The animals that could/would be hunted with this are Whitetail, Mule Deer, Antelope, Hogs and Elk. The max distance id feel comfortable taking a shot at with optimal conditions is about 500yds. what do you guys suggest? Or better, what questions should i ask myself to help narrow the choices down? does the recommendation change if elk is off the list?