TerraN_EmpirE
Tyrant King
To be more exact, the general side turret base armour profile is substantually better armoured than the ones of its contemporaries like the Leo2s or the Type-90.
Ofcourse an APFSDS Round hitting an Abrams from the side will pen that, but when you hit the turret side from a very shallow angle your chances of penetrating are slimmer than those of a Leo2A4 or Type-90.
This should give you an Idea of the Armor design of a tank with a Bustle mounted rack/autoloader. this is the K2 and you can see the "Box" where the Autoloader fits. now the K2 auto loader like that on the Leclarc is only able to hold part of the ammo of the Tank 16 rounds with 24 in the hull. Of the Western Tanks with autoloaders the Type 90 from Japan has the largest capacity in the loader 20 rounds. There were concepts for a Abrams Auto loader with 36 rounds trailed on the Component Advanced Technology Test Bed but they never entered production.
The Main goal and proven is that yes if you can pierce the Bustle rack it's easier to do and the ammo will go. but generally the Crew will have more time to escape or a better chance to live through the event.
The Carousel loader's greatest advantage is also it's key failure point. The System uses the Tanks hull armor for it's protection but that demands that the system is inside the fighting compartment. From armor penetration to a fire in the tank the crew is sitting on a literal powder keg. This and the Unitary ammo is why when the US looked at a Carousel loader in the TTB it was under a unmanned turret.
There is also the ability to repair and replace the Loader and rack if it has been opened. If the loader on a T72 is broken you have to remove the turret for repair or replacement. If a tank with a Bustle loader or rack has a problem it comes right out of the turret.