The 4 tube launcher was speculated on RUssian forums to be launcher for 885 submarines, so I don't think it has anything to do with SAMs. It looked much much bigger than a single 48N6 round.
And it might be... that is irrelevant.
In the photo above I have posted a SAM launcher with four missile positions... three of those missiles positions contain one missile, one of those missile positions contain four missiles.
The Redut system is naval S-400/Vityaz. The single hatch can accommodate one very large missile of the Rif or Rif-M or S-400 type, or it can accommodate four slimmer missiles of the S-400/Vityaz type in one large tube.
It would be totally stupid and totally pointless to have fixed rigid limits on missiles so that a 32 tube launcher could only carry 32 missiles but could carry large heavy missiles or smaller lighter shorter range missiles... there would be no point in carrying only 32 short range missiles when you could carry 32 400km range missiles with much better performance.
To standardise you need scalability... the Redut system can carry big missiles... one to a single tube, it can also carry smaller missiles... Vityaz in four to a tube arrangement the same as the land based version shown above.
I have speculated that the Morfei being a much smaller missile (in between Igla-S and R-74) should be able to carry even more missiles... perhaps in two layers and that is totally speculation on my part I will admit, but it is pretty plain that Redut is a 32 tube system able to carry 32 large missiles or 4 times that in medium sized missiles... we can only guess about small missiles... I am hoping for two layers of 6 missiles but you know what an optimist I am...
4 9m96 might physically fit into the space of one Redut VLS (I'd have to make some measurements) but there are concerns with the launching mechanism as well.
You don't think it will fit?
I showed you a photo of it fitting already...
Again these are self contained launch tubes... loaded onto a truck trailer in this case or into a launch bin on a ship at dock the missile will be packaged exactly the same way for naval applications... the only difference likely will be that the naval missiles will likely plug into the system at their base rather than at their side.
Pretty much every Russian source points to it being one missile, one cell. The only quad pack mention is 9m100, wherever that project is.
Did you read Viktors post above? (no.151)
9M100 is going to be much more like R-60 than R-74 in terms of size but not performance.
32 missiles for 22350, although 4 missiles in a cell is possible per this photo analysis.
2ndly, why Russians install 128 9m96 missiles (range >120km) in a 4500 ton frigate? That is over powered.
Can carry does not mean will carry.
Operationally it will likely carry a mix of short, medium and long range missiles. With 32 tubes that means perhaps 8-12 full sized one missile one tube missiles... lets say 12 because being able to shoot down launch platforms at long range will reduce the number of threats to the vessel during an attack as it can kill aircraft before they launch their weapons. Target detection and tracking can be performed by other platforms or UAVs.
That leaves 20 tubes, but that doesn't mean 80 x medium range SAMs as you will also want short range point defence missiles so maybe 8-12 tubes will be short range self defence missiles to protect from mass attack, which leaves 8-12 tubes for Vityaz missiles... which means 32-48 missiles in the 60km range and 150km range... perhaps a mix of both of 50/50.
Not exactly a revolutionary SAM mix for a Russian vessel but a lot for a 32 tube launch system. For larger vessels the mix will be different but then they will also likely carry more than one bin launcher...
May be 2x9M96 per cell , Four would be cramped as you have to take account the cells these missiles are placed, So likely 2-3 Missile per cell , Even 2 missile per cell would be 64 SAM of 9mM96 which is quite good.
Fitting circles in circles means if you can fit two in then you should be able to get 3 in.
The photo above shows they can clearly get four in. And that they have with the land based model which is fully self contained in its launch container including cold launch system...
The only question I see is how many 9M100s will they fit...