ΔE 14.1, fair: the same colour family, but not a straight swap. Rusty Metal is much more muted than Castellax Bronze.
Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 14). Rusty Metal is much more muted than Castellax Bronze.
The same difference applies the other way round: Castellax Bronze is much 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 Castellax Bronze on the colour wheel See Rusty Metal on the colour wheel
All matches: Castellax Bronze equivalents · Rusty Metal equivalents