ΔE 12.2, fair: the same colour family, but not a straight swap. Red Brown is a little darker, warmer than Deep Khaki Drill.
Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 12). Red Brown is a little darker, warmer than Deep Khaki Drill.
The same difference applies the other way round: Deep Khaki Drill is a little lighter, 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 Deep Khaki Drill on the colour wheel See Red Brown on the colour wheel
All matches: Deep Khaki Drill equivalents · Red Brown equivalents