ΔE 15.4, loose: different enough that you should pick on purpose. Natural Steel is noticeably lighter, more saturated than Black Metal.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 15). Natural Steel is noticeably lighter, more saturated than Black Metal.
The same difference applies the other way round: Black Metal is noticeably darker, 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 Black Metal on the colour wheel See Natural Steel on the colour wheel
All matches: Black Metal equivalents · Natural Steel equivalents