There was also Mineral Gray (early 2003 color). More info HERE. There are two photos at the bottom of the page. But I have to comment that the first photo (Mineral Gray) looks a bit lighter in the photo than it really is. The two color often get confused because they look similar from a certain distance.
Here's another photo of a Mineral Gray Cobra. But because you're calling it Gunmetal Gray, you're probably wanting Dark Shadow Gray. Awesome color, by the way.