ΔE 10.1, fair: the same colour family, but not a straight swap. Ammo Pouch Brown is a little darker than Dirty Grey.
Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 10). Ammo Pouch Brown is a little darker than Dirty Grey.
The same difference applies the other way round: Dirty Grey is a little lighter.
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 Dirty Grey on the colour wheel See Ammo Pouch Brown on the colour wheel
All matches: Dirty Grey equivalents · Ammo Pouch Brown equivalents