Pic relate.

It's got flat rigging because it's assumed you will have to wear it under a rucksack and a Vietnam style chest rig. That way you can just drop the rucksack and be ready to fight. And then you can also drop the battle belt rig wherever you have to set up a forward position and then you've just got your rig with the mags.

But same principle /out/, you drop your rucksack wherever you're camping, take the belt kit out to cut wood/brush/grass and carry a huge bundle back to camp on top of the belt rig similar to how you'd alice pack and that's when the shoulder straps come in clutch.