Sorry, is here somebody from https://thesovietarmourblog.blogspot.com/2017/ ?
I like this blog but whit some statsment hard to agree -but Im not pretend to have absosolut knowledge so I just wanto to discus some thesis about the soviet armour put there.
For example this:
No, it's not.
Kvartz in T-72A and T-72M1 turrets pretend to be not solid, sand, or liquid but somethink known as sintered quartz. And it's definetly not put AFTER casting but before.
Firstly sintered quartz ( quartz sinter) is formed - but whit 3 thick reinforcing bars -then both "kvartz insert" are put to cast form and mounted there by this reinforcing bars -then cast is formed and after taking whole turret those bars are just cut above turret roof line. And thats all.
It's look like this (sory for my amateur draw)
After very havey shelling sometimes this reinforcing bars are "jumping" above roof line -like in Meppen T-72M1 or other hit many times whit penetration in to "kvartz special armour". :