This the original GS05M Gunslinger, a 2700 cubic inch pack with extraordinary features that set it apart from any other mid-size pack. The Back-scabbard is wide enough to hold any type of rifle, including assault rifles and sniper rifles with large scopes.
The Gunslinger is an excellent organizational tool. The layout of its compartments, with a large and a small tuck-pocket on the outside, two small accessory compartments, a mid-size compartment in the top-cover, and a large main compartment that has both top- and full side-access, you can load the pack with your gear in a way that makes it predictable to locate whatever items you need immediate access to.
You can add external mag pouches and accessory pouches virtually anywhere on the pack. On top of this, there is really no way to adequately describe the superiority of this weapons carriage system over the standard shoulder sling.