>>530853152
The backpack visually contains a collection of rifle magazines. There is an elaborate reloading animation where the gun dog docks, ejects the old mag, and then the backpack's mechanisms loads a fresh magazine into the dog. It's neat and you can count the number of spare mags that are on the backpack.
That said, considering the often atrocious lighting conditions in missions THE COULD PUT SOME LIGHTS ON THE BACKPACK OR OTHERWISE IMPROVE THE CONTRAST SO THAT YOU'RE NOT TRYING TO COUNT SMALL BLACK MAGAZINES ON A BLACK BACKDROP OF BLACK RELOADING MECHANIZATION.