RE: I'm looking for a good, big backpack.
Check out blacks creek. I bought the Alaskan. the canadian is a good one too. The compartment is 3000 cubic inches with a small internal frame. The pack zips around the outside and it converts into 4000 cubic inches. It has a spot for a hydration bladder and also a spotting scope. There a zippers with fold out rifle and bow carriers. The pack is fully adjustable for small to extra large frame people to adjust the load to the proper spot. You can use it as a day pack, or pack out meat right from the kill with the same pack when unzipped. I used the heck out of mine last year, and they have a great warranty program.