I am finally working on this kit which I had, but I was originally reluctant due to its scary complexity. I’ve done fine with the barrel after figuring it out (the instructions are a bit confusing), but I noticed that the sight housing is transparent. I have an old Abrams book and a book on the Gulf War, but even they don’t help as to what should be on the “back” of the sight housing transparent area. Silver? Blue? Black?