The case doesn't unzip flat. It unzips from the end and up one side. Basically from directly below the hand strap back up and around to the top corner. It's designed for you slip in your srs. It's fully padded in the walls and seams. It's also really not bulky.
The pockets were designed for certain purposes. There is a pocket for a spare barrel. 4 mag pockets for spare mags, a suppressor pocket for a suppressor, and another pocket for spare bolts and bipod. The back side has a strap and a pocket where the built in back pack straps are all stored if not needed.
That's it. Pretty simple. Everything you need and nothing you don't. Hope this all makes sense.