I have a collection of rather large burlap possible bags which are zippered at the top, for "each caliber." Depending on what I am shooting, I grab that marked bag. Inside the bag is everthing that I might need to break down, clean, shoot, load, etc any rifle of that caliber. Each bag had their own, short starters, powder measure, etc. Besides the bag, then all I need carry to the range is the powder horn. Each kind of powder have their own horn for identification.
I have my leather possible bag for the rendevous I attend, and I hunt out of a camo fanny pack/hand warmer with pockets. It makes it easier to walk around through the brush and to climb trees, etc. The larger hunting pack is loaded prior to the hunt with everything I might need in the field, and there is room for a camera and lunch... ::