I noticed that when using Sildur's Enhanced Default shaders, the muzzle flash of the guns becomes blacked out. I managed to resolve this issue by enabling the light map in your muzzle flash render class. MuzzleFlashRenderType I imagine this might also happen with other shaders as well so thought I would let you know.

Cause seems to be the muzzle flash's lightmap being disabled. Re-enabling then using entity eyes shader should hopefully fix this while keeping max brightness at all light levels