Here’s a question,
As it is known that Chobham, that formed the basis of the first generation of US NERA Developments includes a Plastic strike face & backing layer, and the limited cross-sections we do have of the M1’s arrays don’t delineate between Non-Conventional, Conventional, and Homogeneous armor and said description is broad enough to include plastics.
Would it be a fair assumption to make that it is likely that The “Basic” M1’s Array’s(at very least, as it is specified in the document that the M1A1 uses a different configuration) also contain a similar layer.
Relevant excerpts

Also is it just me or does the quality of the scans, and the reference [PDF page #12]
to the “Tri-plate” (?Three element? ) assembly mentioned in the definition of the Special armor make it look like the middle layer of the composite element that forms each layer is encapsulated, potentially the same way they are as outlined in the Chobham excerpts, which is known to be an unspecified plastic.
I’d report this but using Gaijin’s definition of a spall liner, it doesn’t count.
First up, let’s take a look at what the spall liner is in reality. The spall liner is part of the structural protection of an armored combat vehicle, designed to reduce the damaging effect in the main compartment once a tank is penetrated. To do this, liners are attached inside of the main compartment. Material such as fabrics made from aramid fiber are most often used, but other materials are also used occasionally too.
In the game, the effect of a spall liner is implemented as follows: inside the main fighting compartment, directly after the main portion of a tank’s armor, a module is present that imitates spall liner material.
This is in the sense the issue, where it probably wouldn’t count due to the definition they are using itself, since in effect The Strikeface / Backface encapsulation of the Plate element in the armor would cause some reduction to Spall generation, due to how shock gets transmitted though a dissimilar boundary layer(s).
And I think it would be somewhat more realistic of a measure then simply turning secondary shatters off for the array(s) in question.
To some degree the Pyrophoric properties of DU projectiles would counter these developments due to the Incendiary after armor effect(s), but is a mechanic that is still awaiting implementation.