Here are all the screenshots that show the issue:
[[ http://i.imgur.com/qqhzgiE.jpg | Heres the Woodland Ghillie Suit, Headpiece and Gunwrap on an M4 lying in grass. As you can see it's still black. ]]
[[ http://i.imgur.com/sBXlUls.jpg | Depending on the lightning you can carry around a miniature blackhole on your gun. ]]
[[ http://i.imgur.com/SooJIRN.jpg | Here the Gunwrap took on a Darkgreen/brownish colour. Not as bad as the black hole though, heh. ]]
[[ http://i.imgur.com/yluCtMp.jpg | Heres another one. ]]
The next screenshots will be a lot darker because i switched to a server that just left night time to show the effects of lighting on the Gunwrap.
When it's turning night time the Gunwrap starts to turn Yellow/brown or straight up goes black.
And two more for good measure:
http://i.imgur.com/YsskLFf.jpg http://i.imgur.com/2Vxxya6.jpg