ΔE 14.0, fair: the same colour family, but not a straight swap. US Earth Yellow is a little lighter, warmer than Gun Corps Brown.
Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 14). US Earth Yellow is a little lighter, warmer than Gun Corps Brown.
The same difference applies the other way round: Gun Corps Brown is a little darker, 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 Gun Corps Brown on the colour wheel See US Earth Yellow on the colour wheel
All matches: Gun Corps Brown equivalents · US Earth Yellow equivalents