Another thing that needs to be looked at is the ammo density for some Russian stuff -- look at the BMP-3/BMP-4 and BMD-3/BMD-4.
They have about 35-40 x 100mm rounds plus 500-600 30mm rounds.
If I was able to pull the 30mm 2A72 cannon (84 kg weight) plus it's 500 rounds (200 kg), I'd have 284 kg (626 lbs) that I could devote to little things like fire suppression, spall curtains, etc etc; and maybe some sort of ammo rack for the 100mm ammo; I think I'd be able to make the BMP/BMP sort of not explode in a massive fireball when hit by the average weapon.
But the "combat capability" would be reduced....
