@CryoMask
I'd also like to add that are because the textures for each weapon and image is layered differently.
If you don't know what I mean then this is what I can say:
mtl_t6_wpn_ar_x95l_col means you're editing the base weapon texture
mtl_t6_wpn_ar_x95l_spc-rg~####### means you're editing the weapon texture in a "nacreous" kind of way.
These 2 files layer into each other with the second one being like an overlay technique that doesn't fully change the model itself.
As far as I can tell editing the second file mtl_t6_wpn_ar_x95l_spc-rg~####### at all causes this reflection thing to occur, probably because you're resetting the alpha line on it, but I barely have any clue what alpha is right now so that's my guess.