How do folks buy and fit hunting backpacks?
For other backpacks, I can go to REI or other stores. They will carry several brands and numerous styles. More importantly, they will have experts on-hand to pick a pack with me and then to fit that pack on me. We can work together to get the perfect pack and the perfect fit.
What about hunting packs? Most folks are forced to buy them on-line. I've been quite disappointed by Cabelas. They didn't seem to have any pack experts around. Did I just catch them on a bad day?
Once I had the pack in hand, the videos on the Kifaru website explained how to tweak for custom fit.
I personally know kifaru will work with you on getting a good fit for you. I hear stone glacier will work with you as well. I believe Barney's are built individually to the person. There are some videos on how to fit a pack put out by Aron from kifaru.
Cabelas is great for buying outdoor gear. However I do all my own research before buying there. I will leave it at that.
The differences I AM aware of, is you can get a hunting pack in a camo pattern, and some hunting pack frames can come with several different sizes of bags that attach to the frame. So you can have a small bag to wear while hunting, then swap it out with a large bag for meat hauling or bringing in a backcountry camp.
Another informative resource in addition to those mentioned already can be found at the iTunes store. Listen to the Gritty Bowmen, episode 14, where Aron talks about fitting a pack.