Thread by @VinodDX9

You need different armours for different domains. One can't serve you in all cases. Let's go through a thread . All Russian.

BMP-2M with Berezhok Turret

30 mm autocannon + 2*2 Kornet M ATGM. Good for infantry fighting, well established anti armour capability & it is amphibious!

But still it lacks the adequate fire power to defeat new gen light and medium tanks and heavily armoured IFVs.
So BMP-3M is equipped with a 100 mm 2A70 gun, co-axial 30 mm 2A42 ,a 7.62 PKT MG , two PKT at bow side . The rifled gun fire AT-10 ATGM too, one can mount AT-15 ATGM

The rifled gun has adequate fire punch but has very low rate of fire power. So now BMP-3 us equipped with 57 mm gun, two different variants..

In first pic with Au-220M
In the second it is 2A91

This 57 mm has much fire powr needed to neutralize the threat but has much higher r.o.f than a big gun.
But BMP-3M even has no protection from an enemy MBT. So a heavy IFV T-15 was needed. It has protection than most MBTs around the world!

But T-15 is much heavy. Transportation is a problem. So you need modern day IFV.
Here comes B-11
Epoch Module...30 mm autocannon + 4 Kornet EM ATGM. Better protection than BMP-3M

But even T-15 or B-11 can't give you everything you do need , so you got BMPT Terminator. High elevation if turret gives you capability to counter even in Urban Environment. Besides of those two 30 mm cannon you got 4 Ataka T ATGM too . New Kinzhal module may see 57 mm gun too!

Every thing is good, but what about airborne troops?

You have BMD-4M equipped with 100 mm gun for heavy punch and 30 mm autocannon to neutralize other threats. It will get Kornet D1 ATGM too!

What if you do need to neutralize a tank ?

TADA!

You got Sprut SD. 125 mm gun still overall weight - 18 T.

Russia is thinking to place 2A46-M5 on BMD-4M for additional punch.

Can you believe it? An 18T platform will be able to defeat most modern tanks!

And if you do need MBT?

You got four!

T-14
T-90M
T-80BVM and
T-72B3M

Use according to threat.