Soviet tank crew survival.

[Marcello]

We are speaking about a warhead rated at 600mm against an armor thickness which should not be more than 40mm.That the jet would go throught the bottom should be expected.
The first charge however is typically only a small precursor charge meant to detonate ERA bricks, it should not have the energy to do that.Unless the Javelin has a different internal arrangement,that should be the result of the main charge.