As a sciencist (well, engeneers are science practitioner) I only belief in a good expariment myself. Shells aren't tend to detonate easely and propelland charges are stored in autoloader below the turret projection itself iirc
On the T-72 and T-90 the rounds themselves and propellent stubs are stored in two layers one on top of the other with both stored horizontally with a layer of plate armour on top separating the ammo and propellent from the crew compartment.
On the T-64 and T-80 the ammo is stored lying down horizontally under armour plate but the propellent stubs are stored vertically and are exposed to the open air in the crew compartment.
The propellent stubs have a stub metal case, but the body containing the propellent is propellent impregnated cardboard that is designed to be consumed when the round is fired. It is a semi combustable case so only the metal stub is left after firing.
this means that any spark or red hot metal fragment lands on the cardboard, or touches the cardboard and it is like a spark or red hot metal fragment on a match head... sometimes nothing... sometimes boom.... with lots of fragments inside a turret... boom... all the propellent stubs will go off at once.
When the main gun fires the muzzle flash is the size of the tank... multiply that by 22 and contain it inside the turret and of course that turret will be blow sky high... every time.
A modern Sherman.
Storing ammunition in special boxes on the backside of the turret does not make it impossible to kill the crew through the exploding ammunition stored in boxes on backside of the turret.
Storing ammo and propellent stubs in a metal box that is not flamable would protect ammo and propellent stubs from sparks and hot metal fragments and would prevent a fire or explosion in the case the turret was penetrated.
If a RPG is used from behind like it is possible in urban warfare and the RPG hits the box with ammunition stored lets say on an Abrams, the jet stream will ignite the ammunition, but the jet stream from the RPG warhead will not automatically stop nor will an APFSDS it will still go since there was no virtual protection and it will penetrate the backside of the turret hull, a small hole but where do you guys think the burning and exploding rounds exhaust and fire will go? Path of least resistance, it will go to all holes, to the entrance hole of the RPG, to the exhaust panels and to the hole which enters the tank and combat compartment of the tank.
If we are talking about a small metal box at the rear of the turret ring on the floor then to hit it from behind you would have to accurately shoot through the engine.
If we are talking about rounds stored in a turret bustle then the armour separating the bustle from the crew compartment should allow any propellent explosion to be contained outside the crew area with the blow out panels directing the explosion upwards... the crew would need to get out of the tank because after burning for a few minutes the HEAT rounds will start exploding which will be rather more devastating than the propellent "burning".
Such boxes does not prevent the death of crew if the ammunition explodes they just increase the survivability but the tank is destroyed after that anyway.
Separating the ammo from the crew compartment whether in an autoloader, or armoured box or turret bustle prevents the crew being killed by greatly reducing the risk of explosion and gives them time to escape while the vehicle is burning before the vehicle explodes.