For starters, in Colorado you cannot use sabots or powder in pellet form, nor a scope.

I was there this past season and was shooting a .50 caliber Traditions in-line with 100 gr of 777 2F and a 348 gr Powerbelt Aerotip. I took a nice 5x5 at about 85 yards, after working him for about a half hour before he finally showed himself. The shot was slightly high, but he side stepped and tipped over in his tracks. That worked for me. The bullet lodged on the opposite side and it was a near perfect mushroom.