ΔE 12.2, fair: the same colour family, but not a straight swap. Steel Legion Drab is a little lighter, more muted, warmer than Field Drab (FS30118).
Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 12). Steel Legion Drab is a little lighter, more muted, warmer than Field Drab (FS30118).
The same difference applies the other way round: Field Drab (FS30118) is a little darker, more saturated, cooler.
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 Field Drab (FS30118) on the colour wheel See Steel Legion Drab on the colour wheel
All matches: Field Drab (FS30118) equivalents · Steel Legion Drab equivalents