I started with an old pot of Ral Partha "Parthia Paints" 77-722 'Copper Metallic'. I've had this for close to 20 years, and it's still good. Amazes me how some of those old paints last but GW paints will dry out in less than a year.
Anyway, if you can't find it- as I'm sure it's long OOP, it is a reddish copper, more red than a real copper penny is. But it wasn't as red as I wanted their metal to be, and I wanted to start with a lighter color to work down the shading, so I added to it Vallejo Model Color Old Gold & Vallejo game color silver.. a bit more silver than gold.. gold was to lighten it some and to keep the silver from turning the copper to pink (yellow colors help balance that process). I added some red ink at that point. That made the base color, then I added black & more red ink to it for shadows, weathering was done with thin burnishing of the gold & silver, and glazes of P3 armor wash with a touch of the shadow color, and very thin glazes of blue & green in spots. most of which doesn't show up in photos too well
