Eh … that's very debatable  OD paint was mixed from ochre and black pigments, no green in there, but IMHO it's a brown colour with a green hue, rather than the green colour with a brown hue (or even without) that a lot of people paint their models in. The version of OD used on US Army vehicles faded towards brown when it aged, but I don't know what the type of paint used on aircraft, nor the darker OD used by the USAAF when standard OD was found to be too light for aircraft.