ΔE 14.9, fair: the same colour family, but not a straight swap. Rusty Metal is a little lighter, more muted, warmer than Brass.
Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 15). Rusty Metal is a little lighter, more muted, warmer than Brass.
The same difference applies the other way round: Brass is a little darker, more saturated, 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 Brass on the colour wheel See Rusty Metal on the colour wheel
All matches: Brass equivalents · Rusty Metal equivalents