I tried many rifle holders that hang off your belt, I could not stand having my rifle hang lower then my pack. It always seemed to catch on brush and stuff.
I only pack my rifle when not hunting (hiking out after hours) or when done hunting. Any other time I carry in my hands or sling if I need my hands.
When I want to pack my rifle, I place the butt of my rifle in the "water bottle/side pocket" and strap the barrel with a buckled strap attached up high on the side of my X2.
This holds my rifle securely and completely out of the way.