There is a good answer to this question here: http://www.matadormodels.co.uk/tank_museum/xcamo_ww2ussr.htm
Basically, the consensus is that for Humbrol Enamels, H117 is the best starting point for Soviet 4BO Dark Green used universally during WWII. This is also available in the Humbrol Acrylic range.
"Chip in official records stated in Kolomiets and Morschanski to match FS595b 34102. This is a rich dark green with some olive to it. It’s duller and a little darker than matt wartime British G3 and more grey than their SCC15, although about the same tone. George Hogg has suggested Humbrol 117, and Mike Starmer has this as a mid point, adding 150 to lighten and 116 to darken. The light extreme would be c. 4x117:3x150, the dark 3x117 to 2x116"
116 is also available in acrylic, but 150 may not be? Which is a problem, since it is a key component of an SCC15 mix...