I understand that you are talking about armored casing for the rounds inside the fighting compartment. So if that what you mean, T-90 has this feature and the possibility of turret losing is similar to challenger.
I am sorry if I made a mistake here as I understand challenger way of storing ammo to be inside the fighting compartment, which the pressure vessel in that case.
No, Challenger does store main gun rounds in the crew compartment.
In general, charges and HESH are stored below the turret ring with APFSDS rounds stored in the turret- remember, the Challenger gun uses two part ammunition.
The problem with your comment was that it implied a penetrative hit had occurred and that a "fragment" had caused the ammunition to explode. In fact, it was an entire HESH round dropped through an open turret hatch. Regardless of whether any stored ammunition exploded as a result, I submit that any tank, of any generation, would have been badly inconvenienced by such an event.
Except of course for a MerkaGavin