ΔE 12.9, fair: the same colour family, but not a straight swap. USAF Brown is a little lighter, warmer than Bestial Green.
Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 13). USAF Brown is a little lighter, warmer than Bestial Green.
The same difference applies the other way round: Bestial Green 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 Bestial Green on the colour wheel See USAF Brown on the colour wheel
All matches: Bestial Green equivalents · USAF Brown equivalents