ΔE 13.4, fair: the same colour family, but not a straight swap. Slate Grey is noticeably darker, more muted than Ammo Pouch Brown.
Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 13). Slate Grey is noticeably darker, more muted than Ammo Pouch Brown.
The same difference applies the other way round: Ammo Pouch Brown is noticeably lighter, more saturated.
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 Ammo Pouch Brown on the colour wheel See Slate Grey on the colour wheel
All matches: Ammo Pouch Brown equivalents · Slate Grey equivalents