I think it has something to do with alt col (rough textures for majority of guns) . PaP for mp has everything while victis pap only covers the col of weapons(unless I missed it). Why it's appearing on some guns, and not others not sure should appear on M1911.
As for the muzzle flash I don't really know textures usually comes out black when you made it opaque or placed something on where it shouldn't be. Although it only coming out on FAL and AN94 is pretty weird.
So in conclusion I have no idea I only know how to do textures lmao.