My advise is if that's the gun you shoot well with, don't change just prior to the hunt. Elk are tough, took my first one last November, (5x5) in Rifle, Co. I spent many a day at the local range with my 338 WM, using 250 grain Remington ammo. Thing is your gun WILL shoot differently at altitude AND temperature. Don't sight in you gun in the summer when it's 90 degrees and then expect the same performance at 5 degrees.
I missed the first shot at 505 yards, he gave me a second chance and with a solid hit using a 338 win mag he stood there for what seemed like 5 minutes before falling.
Bench rest is crucial to determine what the gun/ammo is doing. After that, you MUST practice field shots, off the backpack, tri-pod, bi-pod, or whatever you expect to shoot from. Also, shoot some after getting your heart rate elevated because when your guides says "LEGAL BULL TAKE A SHOT", you will have an elevated heart rate!
If you have to fly to the hunt it would be a good idea to shoot your gun after getting there to see how your gun made the trip.