ΔE 20.0, loose: different enough that you should pick on purpose. US Interior Yellow is noticeably lighter, much more saturated, warmer than Gun Corps Brown.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 20). US Interior Yellow is noticeably lighter, much more saturated, warmer than Gun Corps Brown.
The same difference applies the other way round: Gun Corps Brown is noticeably darker, much more muted, 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 Interior Yellow on the colour wheel
All matches: Gun Corps Brown equivalents · US Interior Yellow equivalents