ΔE 10.1, fair: the same colour family, but not a straight swap. Viridian Grim is more muted, cooler than Dark Soviet Khaki.
Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 10). Viridian Grim is more muted, cooler than Dark Soviet Khaki.
The same difference applies the other way round: Dark Soviet Khaki is more saturated, warmer.
ΔE is the colour difference between our two swatch estimates: under about 6 is close, over about 15 is loose. Real paints also differ in finish, coverage and how they thin, so test before you commit.
See Dark Soviet Khaki on the colour wheel See Viridian Grim on the colour wheel
All matches: Dark Soviet Khaki equivalents · Viridian Grim equivalents