The first rack where ammunition is stored in the IS-6 makes no sense. It should be stored in the turret bustle first. It seems very inefficient to store the first 6 shells and propellant next to the driver when the loader is on the other side of the tank. Storing the first 6 in the back of the turret means, this is a lot safer for the crew and loading will be faster. Firstly, if the hull is penetrated, there will be no chance for the ammunition to explode. Because it sits in the back of the turret. Secondly, the loader does not need to squeeze his way past the gunner and commander to get to the left side of the driver and pick up the shells and propellant.