ΔE 15.7, loose: different enough that you should pick on purpose. Steel Legion Drab is a little lighter, more muted, warmer than US Olive Base Uniform.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 16). Steel Legion Drab is a little lighter, more muted, warmer than US Olive Base Uniform.
The same difference applies the other way round: US Olive Base Uniform 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 US Olive Base Uniform on the colour wheel See Steel Legion Drab on the colour wheel
All matches: US Olive Base Uniform equivalents · Steel Legion Drab equivalents