ΔE 15.7, loose: different enough that you should pick on purpose. Semi Gloss Bright Gun Metal is noticeably lighter, more muted, cooler than Cobalt Metal.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 16). Semi Gloss Bright Gun Metal is noticeably lighter, more muted, cooler than Cobalt Metal.
The same difference applies the other way round: Cobalt Metal is noticeably darker, more saturated, warmer.
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 Cobalt Metal on the colour wheel See Semi Gloss Bright Gun Metal on the colour wheel
All matches: Cobalt Metal equivalents · Semi Gloss Bright Gun Metal equivalents