It isn't pitch black, and it reflect light regardless of the source... there are lights in the tunnels.

Even if you shoot out the lights it will still reflect like you have a flash light on you gun.

You can shoot out the lights, like all of them?

Huh... never seen that happen... and I play metro a lot.. of course some of them are broken but...

Then it's just a simple programming issue, a graphical glitch.

Something that's really illogical is shooting a barret 50. while standing... COD logic.

In the part after the first mcoms where you first go into the tunnels, the small service tunnel to the right has lights that can be shot out. I think the reflection should flash at random times.