If you played dayz mod, you definatly remember how you would need to stop to see your inventory and even open the backpack to see the itens inside of it.
The idea is bring something similar to dayz, with more realism than it has today. The backpack would'nt show any slots, you would need to put it in hands and interact with it to open and see it's inventory. This way making players carry mags only in shirts, vests and pants as it should be, also the reload animation should take more or less time, depending where the magazine is stored. A new animation to the caracter checking the pockets when open the inventory (walking or stopped) would be also great.