ΔE 10.2, fair: the same colour family, but not a straight swap. Battlefield Brown is a little darker, more saturated than Strap Grey.
Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 10). Battlefield Brown is a little darker, more saturated than Strap Grey.
The same difference applies the other way round: Strap Grey is a little lighter, more muted.
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 Strap Grey on the colour wheel See Battlefield Brown on the colour wheel
All matches: Strap Grey equivalents · Battlefield Brown equivalents