Battlefront reckon 80/20 Middlestone/US Dark Green, Tom Weiss uses some unspecified mix of US Field Drab and Green Ochre, Artizan go for German Camo Beige or a 'darker' Middlestone. There's a Tamiya spray (AS-15) which is close but not perfect, and hard to come by.
Look what I just found :D
Using the Mac's DigitalColor Meter app, it's pretty close when compared to a range of pictures, around about 125/105/65 R/G/B. If anything it's a smidge dark, but in terms of shade it's the closest I've yet found.