ΔE 27.1, loose: different enough that you should pick on purpose. Bright Brass (Met.) is noticeably lighter, much more muted than Steampunk Copper.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 27). Bright Brass (Met.) is noticeably lighter, much more muted than Steampunk Copper.
The same difference applies the other way round: Steampunk Copper is noticeably darker, 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 Steampunk Copper on the colour wheel See Bright Brass (Met.) on the colour wheel
All matches: Steampunk Copper equivalents · Bright Brass (Met.) equivalents